diff --git a/NEWS.md b/NEWS.md
index 391598f9d..2b1f78492 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -5,7 +5,7 @@
 ### Breaking changes due to Rust-polars update
 
 - rust-polars is updated to 0.38.3 (#937).
-  - New argument `non_existent` in `$replace_time_zone()` to specify what should
+  - New argument `non_existent` in `$dt$replace_time_zone()` to specify what should
     happen when a datetime doesn't exist.
   - In rolling aggregation functions (such as `$rolling_mean()`), the default
     value of argument `closed` now is `NULL`. Using `closed` with a fixed
@@ -20,6 +20,10 @@
     - In `pl$read_*` and `pl$scan_*` functions, the first argument is now `source`.
     - In `<DataFrame>$write_*` functions, the first argument is now `file`.
     - In `<LazyFrame>$sink_*` functions, the first argument is now `path`.
+  - In `$dt$convert_time_zone()` and `$dt$replace_time_zone()`, the `tz` argument
+    is renamed to `time_zone` (#944).
+  - In `$dt$replace_time_zone()`, all arguments except `time_zone` must be named
+    arguments (#944).
 - The argument `columns` in `$drop()` is removed. `$drop()` now accepts several
   character scalars, such as `$drop("a", "b", "c")` (#912).
 - In `pl$col()`, the `name` argument is removed, and the `...` argument no longer
diff --git a/R/as_polars.R b/R/as_polars.R
index 7c5b9ca1c..4ecacae14 100644
--- a/R/as_polars.R
+++ b/R/as_polars.R
@@ -498,16 +498,16 @@ as_polars_series.clock_sys_time = function(x, name = NULL, ...) {
 #' @rdname as_polars_series
 #' @export
 as_polars_series.clock_zoned_time = function(x, name = NULL, ...) {
-  tz = clock::zoned_time_zone(x)
+  time_zone = clock::zoned_time_zone(x)
 
-  if (isTRUE(tz == "")) {
+  if (isTRUE(time_zone == "")) {
     # https://github.com/r-lib/clock/issues/366
-    tz = Sys.timezone()
+    time_zone = Sys.timezone()
   }
-  if (!isTRUE(tz %in% base::OlsonNames())) {
+  if (!isTRUE(time_zone %in% base::OlsonNames())) {
     sprintf(
       "The time zone '%s' is not supported in polars. See `base::OlsonNames()` for supported time zones.",
-      tz
+      time_zone
     ) |>
       Err_plain() |>
       unwrap("in as_polars_series(<clock_zoned_time>):")
@@ -517,5 +517,5 @@ as_polars_series.clock_zoned_time = function(x, name = NULL, ...) {
     clock::as_naive_time(x),
     name = name,
     ...
-  )$dt$replace_time_zone(tz)
+  )$dt$replace_time_zone(time_zone)
 }
diff --git a/R/expr__datetime.R b/R/expr__datetime.R
index e9695b03f..0ae3b6b87 100644
--- a/R/expr__datetime.R
+++ b/R/expr__datetime.R
@@ -641,68 +641,31 @@ ExprDT_cast_time_unit = function(tu = c("ns", "us", "ms")) {
     unwrap()
 }
 
-#' With Time Zone
-#' @description Set time zone for a Series of type Datetime.
-#' Use to change time zone annotation, but keep the corresponding global timepoint.
+#' Convert to given time zone for an expression of type Datetime.
 #'
-#' @param tz String time zone from base::OlsonNames()
+#' If converting from a time-zone-naive datetime,
+#' then conversion will happen as if converting from UTC,
+#' regardless of your system’s time zone.
+#' @param time_zone String time zone from [base::OlsonNames()]
 #' @return Expr of i64
-#' @keywords ExprDT
-#' @details corresponds to in R manually modifying the tzone attribute of POSIXt objects
-#' @aliases (Expr)$dt$convert_time_zone
 #' @examples
 #' df = pl$DataFrame(
-#'   london_timezone = pl$date_range(
+#'   date = pl$date_range(
 #'     as.POSIXct("2020-03-01", tz = "UTC"),
-#'     as.POSIXct("2020-07-01", tz = "UTC"),
-#'     "1mo",
-#'     time_zone = "UTC"
-#'   )$dt$convert_time_zone("Europe/London")
+#'     as.POSIXct("2020-05-01", tz = "UTC"),
+#'     "1mo"
+#'   )
 #' )
 #'
 #' df$select(
-#'   "london_timezone",
-#'   London_to_Amsterdam = pl$col(
-#'     "london_timezone"
-#'   )$dt$replace_time_zone("Europe/Amsterdam")
+#'   "date",
+#'   London = pl$col("date")$dt$convert_time_zone("Europe/London")
 #' )
-#'
-#' # You can use `ambiguous` to deal with ambiguous datetimes:
-#' dates = c(
-#'   "2018-10-28 01:30",
-#'   "2018-10-28 02:00",
-#'   "2018-10-28 02:30",
-#'   "2018-10-28 02:00"
-#' )
-#'
-#' df = pl$DataFrame(
-#'   ts = pl$Series(dates)$str$strptime(pl$Datetime("us"), "%F %H:%M"),
-#'   ambiguous = c("earliest", "earliest", "latest", "latest")
-#' )
-#'
-#' df$with_columns(
-#'   ts_localized = pl$col("ts")$dt$replace_time_zone(
-#'     "Europe/Brussels",
-#'     ambiguous = pl$col("ambiguous")
-#'   )
-#' )
-#'
-#' # Polars Datetime type without a time zone will be converted to R
-#' # with respect to the session time zone. If ambiguous times are present
-#' # an error will be raised. It is recommended to add a time zone before
-#' # converting to R.
-#' s_without_tz = pl$Series(dates)$str$strptime(pl$Datetime("us"), "%F %H:%M")
-#' s_without_tz
-#'
-#' s_with_tz = s_without_tz$dt$replace_time_zone("UTC")
-#' s_with_tz
-#'
-#' as.vector(s_with_tz)
-ExprDT_convert_time_zone = function(tz) {
-  check_tz_to_result(tz) |>
-    map(\(valid_tz) .pr$Expr$dt_convert_time_zone(self, valid_tz)) |>
+ExprDT_convert_time_zone = function(time_zone) {
+  check_tz_to_result(time_zone) |>
+    and_then(\(valid_tz) .pr$Expr$dt_convert_time_zone(self, valid_tz)) |>
     map_err(\(err) paste("in dt$convert_time_zone:", err)) |>
-    unwrap()
+    unwrap("in $convert_time_zone():")
 }
 
 #' Replace time zone
@@ -712,7 +675,8 @@ ExprDT_convert_time_zone = function(tz) {
 #' underlying timestamp. Use to correct a wrong time zone annotation. This will
 #' change the corresponding global timepoint.
 #'
-#' @param tz NULL or string time zone from [base::OlsonNames()]
+#' @param time_zone `NULL` or string time zone from [base::OlsonNames()]
+#' @param ... Ignored.
 #' @param ambiguous Determine how to deal with ambiguous datetimes:
 #' * `"raise"` (default): throw an error
 #' * `"earliest"`: use the earliest datetime
@@ -725,29 +689,43 @@ ExprDT_convert_time_zone = function(tz) {
 #' @keywords ExprDT
 #' @aliases (Expr)$dt$replace_time_zone
 #' @examples
-#' df_1 = pl$DataFrame(x = as.POSIXct("2009-08-07 00:00:01", tz = "America/New_York"))
+#' df1 = pl$DataFrame(
+#'   london_timezone = pl$date_range(
+#'     as.POSIXct("2020-03-01", tz = "UTC"),
+#'     as.POSIXct("2020-07-01", tz = "UTC"),
+#'     "1mo"
+#'   )$dt$convert_time_zone("Europe/London")
+#' )
 #'
-#' df_1$with_columns(
-#'   pl$col("x")$dt$replace_time_zone("UTC")$alias("utc"),
-#'   pl$col("x")$dt$replace_time_zone("Europe/Amsterdam")$alias("cest")
+#' df1$select(
+#'   "london_timezone",
+#'   London_to_Amsterdam = pl$col("london_timezone")$dt$replace_time_zone("Europe/Amsterdam")
 #' )
 #'
-#' # You can use ambiguous to deal with ambiguous datetimes
-#' df_2 = pl$DataFrame(
-#'   x = seq(
-#'     as.POSIXct("2018-10-28 01:30", tz = "UTC"),
-#'     as.POSIXct("2018-10-28 02:30", tz = "UTC"),
-#'     by = "30 min"
-#'   )
+#' # You can use `ambiguous` to deal with ambiguous datetimes:
+#' dates = c(
+#'   "2018-10-28 01:30",
+#'   "2018-10-28 02:00",
+#'   "2018-10-28 02:30",
+#'   "2018-10-28 02:00"
+#' )
+#' df2 = pl$DataFrame(
+#'   ts = as_polars_series(dates)$str$strptime(pl$Datetime("us")),
+#'   ambiguous = c("earliest", "earliest", "latest", "latest")
 #' )
 #'
-#' df_2$with_columns(
-#'   pl$col("x")$dt$replace_time_zone("Europe/Brussels", "earliest")$alias("earliest"),
-#'   pl$col("x")$dt$replace_time_zone("Europe/Brussels", "latest")$alias("latest"),
-#'   pl$col("x")$dt$replace_time_zone("Europe/Brussels", "null")$alias("null")
+#' df2$with_columns(
+#'   ts_localized = pl$col("ts")$dt$replace_time_zone(
+#'     "Europe/Brussels",
+#'     ambiguous = pl$col("ambiguous")
+#'   )
 #' )
-ExprDT_replace_time_zone = function(tz, ambiguous = "raise", non_existent = "raise") {
-  check_tz_to_result(tz) |>
+ExprDT_replace_time_zone = function(
+    time_zone,
+    ...,
+    ambiguous = "raise",
+    non_existent = "raise") {
+  check_tz_to_result(time_zone) |>
     and_then(\(valid_tz) {
       .pr$Expr$dt_replace_time_zone(self, valid_tz, ambiguous, non_existent)
     }) |>
diff --git a/R/extendr-wrappers.R b/R/extendr-wrappers.R
index 4ca637b41..c4b666128 100644
--- a/R/extendr-wrappers.R
+++ b/R/extendr-wrappers.R
@@ -778,9 +778,9 @@ RPolarsExpr$dt_with_time_unit <- function(tu) .Call(wrap__RPolarsExpr__dt_with_t
 
 RPolarsExpr$dt_cast_time_unit <- function(tu) .Call(wrap__RPolarsExpr__dt_cast_time_unit, self, tu)
 
-RPolarsExpr$dt_convert_time_zone <- function(tz) .Call(wrap__RPolarsExpr__dt_convert_time_zone, self, tz)
+RPolarsExpr$dt_convert_time_zone <- function(time_zone) .Call(wrap__RPolarsExpr__dt_convert_time_zone, self, time_zone)
 
-RPolarsExpr$dt_replace_time_zone <- function(tz, ambiguous, non_existent) .Call(wrap__RPolarsExpr__dt_replace_time_zone, self, tz, ambiguous, non_existent)
+RPolarsExpr$dt_replace_time_zone <- function(time_zone, ambiguous, non_existent) .Call(wrap__RPolarsExpr__dt_replace_time_zone, self, time_zone, ambiguous, non_existent)
 
 RPolarsExpr$dt_total_days <- function() .Call(wrap__RPolarsExpr__dt_total_days, self)
 
diff --git a/man/ExprDT_convert_time_zone.Rd b/man/ExprDT_convert_time_zone.Rd
index 27fae6770..3914e8690 100644
--- a/man/ExprDT_convert_time_zone.Rd
+++ b/man/ExprDT_convert_time_zone.Rd
@@ -2,71 +2,32 @@
 % Please edit documentation in R/expr__datetime.R
 \name{ExprDT_convert_time_zone}
 \alias{ExprDT_convert_time_zone}
-\alias{(Expr)$dt$convert_time_zone}
-\title{With Time Zone}
+\title{Convert to given time zone for an expression of type Datetime.}
 \usage{
-ExprDT_convert_time_zone(tz)
+ExprDT_convert_time_zone(time_zone)
 }
 \arguments{
-\item{tz}{String time zone from base::OlsonNames()}
+\item{time_zone}{String time zone from \code{\link[base:timezones]{base::OlsonNames()}}}
 }
 \value{
 Expr of i64
 }
 \description{
-Set time zone for a Series of type Datetime.
-Use to change time zone annotation, but keep the corresponding global timepoint.
-}
-\details{
-corresponds to in R manually modifying the tzone attribute of POSIXt objects
+If converting from a time-zone-naive datetime,
+then conversion will happen as if converting from UTC,
+regardless of your system’s time zone.
 }
 \examples{
 df = pl$DataFrame(
-  london_timezone = pl$date_range(
+  date = pl$date_range(
     as.POSIXct("2020-03-01", tz = "UTC"),
-    as.POSIXct("2020-07-01", tz = "UTC"),
-    "1mo",
-    time_zone = "UTC"
-  )$dt$convert_time_zone("Europe/London")
+    as.POSIXct("2020-05-01", tz = "UTC"),
+    "1mo"
+  )
 )
 
 df$select(
-  "london_timezone",
-  London_to_Amsterdam = pl$col(
-    "london_timezone"
-  )$dt$replace_time_zone("Europe/Amsterdam")
-)
-
-# You can use `ambiguous` to deal with ambiguous datetimes:
-dates = c(
-  "2018-10-28 01:30",
-  "2018-10-28 02:00",
-  "2018-10-28 02:30",
-  "2018-10-28 02:00"
-)
-
-df = pl$DataFrame(
-  ts = pl$Series(dates)$str$strptime(pl$Datetime("us"), "\%F \%H:\%M"),
-  ambiguous = c("earliest", "earliest", "latest", "latest")
+  "date",
+  London = pl$col("date")$dt$convert_time_zone("Europe/London")
 )
-
-df$with_columns(
-  ts_localized = pl$col("ts")$dt$replace_time_zone(
-    "Europe/Brussels",
-    ambiguous = pl$col("ambiguous")
-  )
-)
-
-# Polars Datetime type without a time zone will be converted to R
-# with respect to the session time zone. If ambiguous times are present
-# an error will be raised. It is recommended to add a time zone before
-# converting to R.
-s_without_tz = pl$Series(dates)$str$strptime(pl$Datetime("us"), "\%F \%H:\%M")
-s_without_tz
-
-s_with_tz = s_without_tz$dt$replace_time_zone("UTC")
-s_with_tz
-
-as.vector(s_with_tz)
 }
-\keyword{ExprDT}
diff --git a/man/ExprDT_replace_time_zone.Rd b/man/ExprDT_replace_time_zone.Rd
index 489749c7a..449ac3fd4 100644
--- a/man/ExprDT_replace_time_zone.Rd
+++ b/man/ExprDT_replace_time_zone.Rd
@@ -5,10 +5,17 @@
 \alias{(Expr)$dt$replace_time_zone}
 \title{Replace time zone}
 \usage{
-ExprDT_replace_time_zone(tz, ambiguous = "raise", non_existent = "raise")
+ExprDT_replace_time_zone(
+  time_zone,
+  ...,
+  ambiguous = "raise",
+  non_existent = "raise"
+)
 }
 \arguments{
-\item{tz}{NULL or string time zone from \code{\link[base:timezones]{base::OlsonNames()}}}
+\item{time_zone}{\code{NULL} or string time zone from \code{\link[base:timezones]{base::OlsonNames()}}}
+
+\item{...}{Ignored.}
 
 \item{ambiguous}{Determine how to deal with ambiguous datetimes:
 \itemize{
@@ -34,26 +41,36 @@ underlying timestamp. Use to correct a wrong time zone annotation. This will
 change the corresponding global timepoint.
 }
 \examples{
-df_1 = pl$DataFrame(x = as.POSIXct("2009-08-07 00:00:01", tz = "America/New_York"))
+df1 = pl$DataFrame(
+  london_timezone = pl$date_range(
+    as.POSIXct("2020-03-01", tz = "UTC"),
+    as.POSIXct("2020-07-01", tz = "UTC"),
+    "1mo"
+  )$dt$convert_time_zone("Europe/London")
+)
 
-df_1$with_columns(
-  pl$col("x")$dt$replace_time_zone("UTC")$alias("utc"),
-  pl$col("x")$dt$replace_time_zone("Europe/Amsterdam")$alias("cest")
+df1$select(
+  "london_timezone",
+  London_to_Amsterdam = pl$col("london_timezone")$dt$replace_time_zone("Europe/Amsterdam")
 )
 
-# You can use ambiguous to deal with ambiguous datetimes
-df_2 = pl$DataFrame(
-  x = seq(
-    as.POSIXct("2018-10-28 01:30", tz = "UTC"),
-    as.POSIXct("2018-10-28 02:30", tz = "UTC"),
-    by = "30 min"
-  )
+# You can use `ambiguous` to deal with ambiguous datetimes:
+dates = c(
+  "2018-10-28 01:30",
+  "2018-10-28 02:00",
+  "2018-10-28 02:30",
+  "2018-10-28 02:00"
+)
+df2 = pl$DataFrame(
+  ts = as_polars_series(dates)$str$strptime(pl$Datetime("us")),
+  ambiguous = c("earliest", "earliest", "latest", "latest")
 )
 
-df_2$with_columns(
-  pl$col("x")$dt$replace_time_zone("Europe/Brussels", "earliest")$alias("earliest"),
-  pl$col("x")$dt$replace_time_zone("Europe/Brussels", "latest")$alias("latest"),
-  pl$col("x")$dt$replace_time_zone("Europe/Brussels", "null")$alias("null")
+df2$with_columns(
+  ts_localized = pl$col("ts")$dt$replace_time_zone(
+    "Europe/Brussels",
+    ambiguous = pl$col("ambiguous")
+  )
 )
 }
 \keyword{ExprDT}
diff --git a/src/rust/src/lazy/dsl.rs b/src/rust/src/lazy/dsl.rs
index 95a51ccee..573e6e0f1 100644
--- a/src/rust/src/lazy/dsl.rs
+++ b/src/rust/src/lazy/dsl.rs
@@ -1440,18 +1440,24 @@ impl RPolarsExpr {
         ))
     }
 
-    pub fn dt_convert_time_zone(&self, tz: String) -> Self {
-        self.0.clone().dt().convert_time_zone(tz).into()
+    pub fn dt_convert_time_zone(&self, time_zone: Robj) -> RResult<RPolarsExpr> {
+        Ok(RPolarsExpr(
+            self.0
+                .clone()
+                .dt()
+                .convert_time_zone(robj_to!(String, time_zone)?)
+                .into(),
+        ))
     }
 
     pub fn dt_replace_time_zone(
         &self,
-        tz: Nullable<String>,
+        time_zone: Nullable<String>,
         ambiguous: Robj,
         non_existent: Robj,
     ) -> RResult<Self> {
         Ok(RPolarsExpr(self.0.clone().dt().replace_time_zone(
-            tz.into_option(),
+            time_zone.into_option(),
             robj_to!(PLExpr, ambiguous)?,
             robj_to!(NonExistent, non_existent)?,
         )))
diff --git a/tests/testthat/test-expr_datetime.R b/tests/testthat/test-expr_datetime.R
index a9dc52cc8..75f26b668 100644
--- a/tests/testthat/test-expr_datetime.R
+++ b/tests/testthat/test-expr_datetime.R
@@ -697,9 +697,9 @@ test_that("replace_time_zone for ambiguous time", {
   x = seq(as.POSIXct("2018-10-28 01:30", tz = "UTC"), as.POSIXct("2018-10-28 02:30", tz = "UTC"), by = "30 min")
 
   pl_out = pl$DataFrame(x = x)$with_columns(
-    pl$col("x")$dt$replace_time_zone("Europe/Brussels", "earliest")$alias("earliest"),
-    pl$col("x")$dt$replace_time_zone("Europe/Brussels", "latest")$alias("latest"),
-    pl$col("x")$dt$replace_time_zone("Europe/Brussels", "null")$alias("null")
+    pl$col("x")$dt$replace_time_zone("Europe/Brussels", ambiguous = "earliest")$alias("earliest"),
+    pl$col("x")$dt$replace_time_zone("Europe/Brussels", ambiguous = "latest")$alias("latest"),
+    pl$col("x")$dt$replace_time_zone("Europe/Brussels", ambiguous = "null")$alias("null")
   )$to_data_frame()
 
   lubridate_out = data.frame(