diff --git a/src/Dictionary/getIn.lua b/src/Dictionary/getIn.lua
new file mode 100644
index 0000000..d205287
--- /dev/null
+++ b/src/Dictionary/getIn.lua
@@ -0,0 +1,15 @@
+return function(dictionary, keyPath, default)
+	local dictionaryType = type(dictionary)
+	assert(dictionaryType == "table", "expected a table for first argument, got " .. dictionaryType)
+	assert(type(keyPath) == "table", string.format("Invalid keyPath: expected array: %s", tostring(keyPath)))
+
+	local node = dictionary
+	for _, path in ipairs(keyPath) do
+		node = node[path]
+		if not node then
+			return default
+		end
+	end
+
+	return node
+end
diff --git a/src/Dictionary/init.lua b/src/Dictionary/init.lua
index a823644..1ef8e90 100644
--- a/src/Dictionary/init.lua
+++ b/src/Dictionary/init.lua
@@ -11,18 +11,22 @@ local Dictionary = {
 	flatten = require(script.flatten),
 	flip = require(script.flip),
 	get = require(script.get),
+	getIn = require(script.getIn),
 	has = require(script.has),
 	includes = require(script.includes),
 	join = require(script.join),
 	joinDeep = require(script.joinDeep),
 	keys = require(script.keys),
 	map = require(script.map),
+	removeIn = require(script.removeIn),
 	removeKey = require(script.removeKey),
 	removeValue = require(script.removeValue),
 	set = require(script.set),
+	setIn = require(script.setIn),
 	some = require(script.some),
 	update = require(script.update),
+	updateIn = require(script.updateIn),
 	values = require(script.values),
 }
 
-return Dictionary
\ No newline at end of file
+return Dictionary
diff --git a/src/Dictionary/removeIn.lua b/src/Dictionary/removeIn.lua
new file mode 100644
index 0000000..5715b07
--- /dev/null
+++ b/src/Dictionary/removeIn.lua
@@ -0,0 +1,7 @@
+local updateIn = require(script.Parent.updateIn)
+
+return function(dictionary, keyPath)
+	return updateIn(dictionary, keyPath, function()
+		return nil
+	end, nil)
+end
diff --git a/src/Dictionary/setIn.lua b/src/Dictionary/setIn.lua
new file mode 100644
index 0000000..6260085
--- /dev/null
+++ b/src/Dictionary/setIn.lua
@@ -0,0 +1,9 @@
+local updateIn = require(script.Parent.updateIn)
+
+return function(dictionary, keyPath, value)
+	local result = updateIn(dictionary, keyPath, function()
+		return value
+	end, {})
+
+	return result
+end
diff --git a/src/Dictionary/updateIn.lua b/src/Dictionary/updateIn.lua
new file mode 100644
index 0000000..7ae6604
--- /dev/null
+++ b/src/Dictionary/updateIn.lua
@@ -0,0 +1,65 @@
+local removeKey = require(script.Parent.removeKey)
+local set = require(script.Parent.set)
+local map = require(script.Parent.map)
+local slice = require(script.Parent.Parent.List.slice)
+
+local function quoteString(value)
+	return string.format("%q", value)
+end
+
+local function throw(existing, keyPath, i)
+	error(string.format(
+		"Cannot update within non-table value in path [%s] = %s",
+		table.concat(map(slice(keyPath, 1, i - 1), quoteString), ", "),
+		tostring(existing)
+	))
+end
+
+local function updateInDeeply(existing, keyPath, notSetValue, updater, i)
+	local wasNotSet = existing == nil
+	if i > #keyPath then
+		local existingValue = wasNotSet and notSetValue or existing
+		local newValue = updater(existingValue)
+		return newValue == existingValue and existing or newValue
+	end
+
+	if (not wasNotSet and type(existing) ~= "table") then
+		throw(existing, keyPath, i)
+	end
+
+	local key = keyPath[i]
+	local nextExisting
+	if wasNotSet then
+		nextExisting = notSetValue and notSetValue[key] or nil
+	else
+		nextExisting = existing[key]
+	end
+
+	local nextUpdated = updateInDeeply(nextExisting, keyPath, notSetValue, updater, i + 1)
+
+	if nextUpdated == nil then
+		if existing or notSetValue then
+			return removeKey(existing or notSetValue, key)
+		end
+	else
+		if existing or notSetValue then
+			return set(existing or notSetValue, key, nextUpdated)
+		else
+			throw(existing, keyPath, i)
+		end
+	end
+
+	return nil
+end
+
+return function(dictionary, keyPath, updater, notSetValue)
+	local dictionaryType = type(dictionary)
+	assert(dictionaryType == "table", "expected a table for first argument, got " .. dictionaryType)
+	assert(type(keyPath) == "table", string.format("Invalid keyPath: expected array: %s", tostring(keyPath)))
+
+	local updatedValue = updateInDeeply(
+		dictionary, keyPath, notSetValue, updater, 1
+	)
+
+	return updatedValue or notSetValue
+end
diff --git a/tests/Llama/Dictionary/getIn.spec.lua b/tests/Llama/Dictionary/getIn.spec.lua
new file mode 100644
index 0000000..291c671
--- /dev/null
+++ b/tests/Llama/Dictionary/getIn.spec.lua
@@ -0,0 +1,46 @@
+return function()
+	local ReplicatedStorage = game:GetService("ReplicatedStorage")
+	local lib = ReplicatedStorage.lib
+	local Llama = require(lib.Llama)
+	local getIn = Llama.Dictionary.getIn
+
+	describe("GIVEN a dictionary with layers x, y, and z", function()
+		local dictionary = { x = { y = { z = 123 }}}
+
+		it("SHOULD return 123 when given {x, y, z}", function()
+			local result = getIn(dictionary, {"x", "y", "z"})
+			expect(result).to.equal(123)
+		end)
+
+		it("SHOULD return the given default when given {x, q, p}", function()
+			local result = getIn(dictionary, {"x", "q", "p"}, "someDefaultValue")
+			expect(result).to.equal("someDefaultValue")
+		end)
+
+		it("SHOULD return nil if path does not match and there is no default given", function()
+			expect(getIn(dictionary, {"a", "b", "c"})).to.equal(nil)
+			expect(getIn(dictionary, {"x", "b", "c"})).to.equal(nil)
+			expect(getIn(dictionary, {"x", "y", "c"})).to.equal(nil)
+		end)
+
+		it("SHOULD return not found if path encounters non-data-structure", function()
+			local m = { a = { b = { c = nil }}}
+			local keyPath = { "a", "b", "c", "x" }
+			expect(getIn(m, keyPath)).to.equal(nil)
+			expect(getIn(m, keyPath, "default")).to.equal("default")
+		end)
+	end)
+
+	local function itShouldThrowAsKeyPath(given)
+		return function()
+			it("SHOULD throw", function()
+				expect(function()
+					getIn({}, given)
+				end).to.throw()
+			end)
+		end
+	end
+	describe("GIVEN a number as keyPath", itShouldThrowAsKeyPath(10))
+	describe("GIVEN string as keyPath", itShouldThrowAsKeyPath("abc"))
+	describe("GIVEN nil as keyPath", itShouldThrowAsKeyPath(nil))
+end
diff --git a/tests/Llama/Dictionary/removeIn.spec.lua b/tests/Llama/Dictionary/removeIn.spec.lua
new file mode 100644
index 0000000..cd86fdd
--- /dev/null
+++ b/tests/Llama/Dictionary/removeIn.spec.lua
@@ -0,0 +1,26 @@
+return function()
+	local ReplicatedStorage = game:GetService("ReplicatedStorage")
+
+	local lib = ReplicatedStorage.lib
+	local Llama = require(lib.Llama)
+
+	local Dictionary = Llama.Dictionary
+	local removeIn = Dictionary.removeIn
+	local equalsDeep = Dictionary.equalsDeep
+
+	it("provides shorthand for updateIn to remove a single value", function()
+		local m = { a = { b = { c = "X", d = "Y" } } }
+		local result = removeIn(m, { "a", "b", "c" })
+		expect(equalsDeep(result, { a = { b = { d = "Y" }} })).to.equal(true)
+	end)
+
+	it("does not create empty maps for an unset path", function()
+		local result = removeIn({}, { "a", "b", "c" })
+		expect(equalsDeep(result, {})).to.equal(true)
+	end)
+
+	it("removes itself when removing empty path", function()
+		local m = {}
+		expect(removeIn({}, {})).to.never.be.ok()
+	end)
+end
diff --git a/tests/Llama/Dictionary/setIn.spec.lua b/tests/Llama/Dictionary/setIn.spec.lua
new file mode 100644
index 0000000..2688636
--- /dev/null
+++ b/tests/Llama/Dictionary/setIn.spec.lua
@@ -0,0 +1,25 @@
+return function()
+	local ReplicatedStorage = game:GetService("ReplicatedStorage")
+
+	local lib = ReplicatedStorage.lib
+	local Llama = require(lib.Llama)
+
+	local Dictionary = Llama.Dictionary
+	local setIn = Dictionary.setIn
+	local equalsDeep = Dictionary.equalsDeep
+
+	it("provides shorthand for updateIn to set a single value", function()
+		local m = setIn({}, { "a", "b", "c" }, "X");
+		expect(equalsDeep(m, { a = { b = { c = "X" }} })).to.equal(true)
+	end)
+
+	it("returns value when setting empty path", function()
+		local m = {}
+		expect(setIn({}, {}, "X")).to.equal("X");
+	end)
+
+	it("can setIn nil", function()
+		local m = setIn({}, { "a", "b", "c" }, nil);
+		expect(equalsDeep(m, { a = { b = { c = nil }} })).to.equal(true)
+	end)
+end
diff --git a/tests/Llama/Dictionary/updateIn.spec.lua b/tests/Llama/Dictionary/updateIn.spec.lua
new file mode 100644
index 0000000..121ac6c
--- /dev/null
+++ b/tests/Llama/Dictionary/updateIn.spec.lua
@@ -0,0 +1,111 @@
+return function()
+	local ReplicatedStorage = game:GetService("ReplicatedStorage")
+
+	local lib = ReplicatedStorage.lib
+	local Llama = require(lib.Llama)
+
+	local Dictionary = Llama.Dictionary
+	local updateIn = Dictionary.updateIn
+	local equalsDeep = Dictionary.equalsDeep
+
+	it("deep edit", function()
+		local m = { a = { b = { c = 10 }}}
+		local result = updateIn(m, {"a", "b", "c"}, function(value)
+			return value * 2
+		end)
+
+		expect(equalsDeep(result, { a = { b = { c = 20 }}})).to.equal(true)
+	end)
+
+	it("deep edit throws if non-editable path", function()
+		local deep = { key = { bar = { item = 10 }} }
+		expect(function()
+			updateIn(deep, {"key", "foo", "item"}, function()
+				return "newValue"
+			end)
+		end).to.throw("Cannot update within non-table value in path")
+	end)
+
+	it("shallow remove", function()
+		local m = { a = 123 }
+		local result = updateIn(m, {"a"}, function()
+			return nil
+		end)
+		expect(equalsDeep(result, {})).to.equal(true)
+	end)
+
+	it("deep remove", function()
+		local removeKey = Dictionary.removeKey
+
+		local m = { a = { b = { c = 10 } } }
+		local result = updateIn(m, {"a", "b"}, function(map)
+			return removeKey(map, "c")
+		end)
+		expect(equalsDeep(result, { a = { b = {} }})).to.equal(true)
+	end)
+
+	it("deep set", function()
+		local set = Dictionary.set
+
+		local m = { a = { b = { c = 10 } } }
+		local result = updateIn(m, {"a", "b"}, function(map)
+			return set(map, "d", 20)
+		end)
+		expect(equalsDeep(result, { a = { b = { c = 10, d = 20 } }})).to.equal(true)
+	end)
+
+	it("deep push", function()
+		local push = Llama.List.push
+		local m = { a = { b = { 1, 2, 3 }}}
+		local result = updateIn(m, {"a", "b"}, function(list)
+			return push(list, 4)
+		end)
+		expect(equalsDeep(result, { a = { b = { 1, 2, 3, 4 } }})).to.equal(true)
+	end)
+
+	it("deep map", function()
+		local map = Llama.List.map
+		local m = { a = { b = { 1, 2, 3 }}}
+		local result = updateIn(m, {"a", "b"}, function(list)
+			return map(list, function(value)
+				return value * 10
+			end)
+		end)
+		expect(equalsDeep(result, { a = { b = { 10, 20, 30 } }})).to.equal(true)
+	end)
+
+	it("creates new maps if path contains gaps", function()
+		local set = Llama.Dictionary.set
+		local m = { a = { b = { c = 10 }}}
+		local result = updateIn(m, { "a", "x", "y" }, function(map)
+			return set(map, "z", 20)
+		end, {})
+		expect(equalsDeep(result, { a = { b = { c = 10 }, x = { y = { z = 20 }} }})).to.equal(true)
+	end)
+
+	it("throws if path cannot be set", function()
+		local m = { a = { b = { c = 10 } } }
+		expect(function()
+			updateIn(m, { "a", "b", "c", "d" }, function(v)
+				return 20
+			end)
+		end).to.throw("Cannot update within non-table value in path")
+	end)
+
+	it("update with notSetValue when non-existing key", function()
+		local m = { a = { b = { c = 10 } } }
+		local result = updateIn(m, {"x"}, function(map)
+			return map + 1
+		end, 100)
+		expect(equalsDeep(result, { x = 101, a = { b = { c = 10 } }})).to.equal(true)
+	end)
+
+	it("updates self for empty path", function()
+		local set = Llama.Dictionary.set
+		local m = { a = 1, b = 2, c = 3 }
+		local result = updateIn(m, {}, function(map)
+			return set(map, "b", 20)
+		end)
+		expect(equalsDeep(result, { a = 1, b = 20, c = 3 })).to.equal(true)
+	end)
+end