diff --git a/cty/convert/conversion_collection.go b/cty/convert/conversion_collection.go
index 1b0678bf..ea23bf61 100644
--- a/cty/convert/conversion_collection.go
+++ b/cty/convert/conversion_collection.go
@@ -15,18 +15,18 @@ func conversionCollectionToList(ety cty.Type, conv conversion) conversion {
 	return func(val cty.Value, path cty.Path) (cty.Value, error) {
 		elems := make([]cty.Value, 0, val.LengthInt())
 		i := int64(0)
-		path = append(path, nil)
+		elemPath := append(path.Copy(), nil)
 		it := val.ElementIterator()
 		for it.Next() {
 			_, val := it.Element()
 			var err error
 
-			path[len(path)-1] = cty.IndexStep{
+			elemPath[len(elemPath)-1] = cty.IndexStep{
 				Key: cty.NumberIntVal(i),
 			}
 
 			if conv != nil {
-				val, err = conv(val, path)
+				val, err = conv(val, elemPath)
 				if err != nil {
 					return cty.NilVal, err
 				}
@@ -37,6 +37,9 @@ func conversionCollectionToList(ety cty.Type, conv conversion) conversion {
 		}
 
 		if len(elems) == 0 {
+			if ety == cty.DynamicPseudoType {
+				ety = val.Type().ElementType()
+			}
 			return cty.ListValEmpty(ety), nil
 		}
 
@@ -55,18 +58,18 @@ func conversionCollectionToSet(ety cty.Type, conv conversion) conversion {
 	return func(val cty.Value, path cty.Path) (cty.Value, error) {
 		elems := make([]cty.Value, 0, val.LengthInt())
 		i := int64(0)
-		path = append(path, nil)
+		elemPath := append(path.Copy(), nil)
 		it := val.ElementIterator()
 		for it.Next() {
 			_, val := it.Element()
 			var err error
 
-			path[len(path)-1] = cty.IndexStep{
+			elemPath[len(elemPath)-1] = cty.IndexStep{
 				Key: cty.NumberIntVal(i),
 			}
 
 			if conv != nil {
-				val, err = conv(val, path)
+				val, err = conv(val, elemPath)
 				if err != nil {
 					return cty.NilVal, err
 				}
@@ -77,6 +80,11 @@ func conversionCollectionToSet(ety cty.Type, conv conversion) conversion {
 		}
 
 		if len(elems) == 0 {
+			// Prefer a concrete type over a dynamic type when returning an
+			// empty set
+			if ety == cty.DynamicPseudoType {
+				ety = val.Type().ElementType()
+			}
 			return cty.SetValEmpty(ety), nil
 		}
 
@@ -93,13 +101,13 @@ func conversionCollectionToSet(ety cty.Type, conv conversion) conversion {
 func conversionCollectionToMap(ety cty.Type, conv conversion) conversion {
 	return func(val cty.Value, path cty.Path) (cty.Value, error) {
 		elems := make(map[string]cty.Value, 0)
-		path = append(path, nil)
+		elemPath := append(path.Copy(), nil)
 		it := val.ElementIterator()
 		for it.Next() {
 			key, val := it.Element()
 			var err error
 
-			path[len(path)-1] = cty.IndexStep{
+			elemPath[len(elemPath)-1] = cty.IndexStep{
 				Key: key,
 			}
 
@@ -107,11 +115,11 @@ func conversionCollectionToMap(ety cty.Type, conv conversion) conversion {
 			if err != nil {
 				// Should never happen, because keys can only be numbers or
 				// strings and both can convert to string.
-				return cty.DynamicVal, path.NewErrorf("cannot convert key type %s to string for map", key.Type().FriendlyName())
+				return cty.DynamicVal, elemPath.NewErrorf("cannot convert key type %s to string for map", key.Type().FriendlyName())
 			}
 
 			if conv != nil {
-				val, err = conv(val, path)
+				val, err = conv(val, elemPath)
 				if err != nil {
 					return cty.NilVal, err
 				}
@@ -121,9 +129,25 @@ func conversionCollectionToMap(ety cty.Type, conv conversion) conversion {
 		}
 
 		if len(elems) == 0 {
+			// Prefer a concrete type over a dynamic type when returning an
+			// empty map
+			if ety == cty.DynamicPseudoType {
+				ety = val.Type().ElementType()
+			}
 			return cty.MapValEmpty(ety), nil
 		}
 
+		if ety.IsCollectionType() || ety.IsObjectType() {
+			var err error
+			if elems, err = conversionUnifyCollectionElements(elems, path, false); err != nil {
+				return cty.NilVal, err
+			}
+		}
+
+		if err := conversionCheckMapElementTypes(elems, path); err != nil {
+			return cty.NilVal, err
+		}
+
 		return cty.MapVal(elems), nil
 	}
 }
@@ -171,20 +195,20 @@ func conversionTupleToSet(tupleType cty.Type, listEty cty.Type, unsafe bool) con
 	// element conversions in elemConvs
 	return func(val cty.Value, path cty.Path) (cty.Value, error) {
 		elems := make([]cty.Value, 0, len(elemConvs))
-		path = append(path, nil)
+		elemPath := append(path.Copy(), nil)
 		i := int64(0)
 		it := val.ElementIterator()
 		for it.Next() {
 			_, val := it.Element()
 			var err error
 
-			path[len(path)-1] = cty.IndexStep{
+			elemPath[len(elemPath)-1] = cty.IndexStep{
 				Key: cty.NumberIntVal(i),
 			}
 
 			conv := elemConvs[i]
 			if conv != nil {
-				val, err = conv(val, path)
+				val, err = conv(val, elemPath)
 				if err != nil {
 					return cty.NilVal, err
 				}
@@ -241,20 +265,20 @@ func conversionTupleToList(tupleType cty.Type, listEty cty.Type, unsafe bool) co
 	// element conversions in elemConvs
 	return func(val cty.Value, path cty.Path) (cty.Value, error) {
 		elems := make([]cty.Value, 0, len(elemConvs))
-		path = append(path, nil)
+		elemPath := append(path.Copy(), nil)
 		i := int64(0)
 		it := val.ElementIterator()
 		for it.Next() {
 			_, val := it.Element()
 			var err error
 
-			path[len(path)-1] = cty.IndexStep{
+			elemPath[len(elemPath)-1] = cty.IndexStep{
 				Key: cty.NumberIntVal(i),
 			}
 
 			conv := elemConvs[i]
 			if conv != nil {
-				val, err = conv(val, path)
+				val, err = conv(val, elemPath)
 				if err != nil {
 					return cty.NilVal, err
 				}
@@ -315,19 +339,19 @@ func conversionObjectToMap(objectType cty.Type, mapEty cty.Type, unsafe bool) co
 	// element conversions in elemConvs
 	return func(val cty.Value, path cty.Path) (cty.Value, error) {
 		elems := make(map[string]cty.Value, len(elemConvs))
-		path = append(path, nil)
+		elemPath := append(path.Copy(), nil)
 		it := val.ElementIterator()
 		for it.Next() {
 			name, val := it.Element()
 			var err error
 
-			path[len(path)-1] = cty.IndexStep{
+			elemPath[len(elemPath)-1] = cty.IndexStep{
 				Key: name,
 			}
 
 			conv := elemConvs[name.AsString()]
 			if conv != nil {
-				val, err = conv(val, path)
+				val, err = conv(val, elemPath)
 				if err != nil {
 					return cty.NilVal, err
 				}
@@ -335,6 +359,17 @@ func conversionObjectToMap(objectType cty.Type, mapEty cty.Type, unsafe bool) co
 			elems[name.AsString()] = val
 		}
 
+		if mapEty.IsCollectionType() || mapEty.IsObjectType() {
+			var err error
+			if elems, err = conversionUnifyCollectionElements(elems, path, unsafe); err != nil {
+				return cty.NilVal, err
+			}
+		}
+
+		if err := conversionCheckMapElementTypes(elems, path); err != nil {
+			return cty.NilVal, err
+		}
+
 		return cty.MapVal(elems), nil
 	}
 }
@@ -368,7 +403,7 @@ func conversionMapToObject(mapType cty.Type, objType cty.Type, unsafe bool) conv
 	// element conversions in elemConvs
 	return func(val cty.Value, path cty.Path) (cty.Value, error) {
 		elems := make(map[string]cty.Value, len(elemConvs))
-		path = append(path, nil)
+		elemPath := append(path.Copy(), nil)
 		it := val.ElementIterator()
 		for it.Next() {
 			name, val := it.Element()
@@ -380,13 +415,13 @@ func conversionMapToObject(mapType cty.Type, objType cty.Type, unsafe bool) conv
 
 			var err error
 
-			path[len(path)-1] = cty.IndexStep{
+			elemPath[len(elemPath)-1] = cty.IndexStep{
 				Key: name,
 			}
 
 			conv := elemConvs[name.AsString()]
 			if conv != nil {
-				val, err = conv(val, path)
+				val, err = conv(val, elemPath)
 				if err != nil {
 					return cty.NilVal, err
 				}
@@ -398,3 +433,56 @@ func conversionMapToObject(mapType cty.Type, objType cty.Type, unsafe bool) conv
 		return cty.ObjectVal(elems), nil
 	}
 }
+
+func conversionUnifyCollectionElements(elems map[string]cty.Value, path cty.Path, unsafe bool) (map[string]cty.Value, error) {
+	elemTypes := make([]cty.Type, 0, len(elems))
+	for _, elem := range elems {
+		elemTypes = append(elemTypes, elem.Type())
+	}
+	unifiedType, _ := unify(elemTypes, unsafe)
+	if unifiedType == cty.NilType {
+	}
+
+	unifiedElems := make(map[string]cty.Value)
+	elemPath := append(path.Copy(), nil)
+
+	for name, elem := range elems {
+		if elem.Type().Equals(unifiedType) {
+			unifiedElems[name] = elem
+			continue
+		}
+		conv := getConversion(elem.Type(), unifiedType, unsafe)
+		if conv == nil {
+		}
+		elemPath[len(elemPath)-1] = cty.IndexStep{
+			Key: cty.StringVal(name),
+		}
+		val, err := conv(elem, elemPath)
+		if err != nil {
+			return nil, err
+		}
+		unifiedElems[name] = val
+	}
+
+	return unifiedElems, nil
+}
+
+func conversionCheckMapElementTypes(elems map[string]cty.Value, path cty.Path) error {
+	elementType := cty.NilType
+	elemPath := append(path.Copy(), nil)
+
+	for name, elem := range elems {
+		if elementType == cty.NilType {
+			elementType = elem.Type()
+			continue
+		}
+		if !elementType.Equals(elem.Type()) {
+			elemPath[len(elemPath)-1] = cty.IndexStep{
+				Key: cty.StringVal(name),
+			}
+			return elemPath.NewErrorf("%s is required", elementType.FriendlyName())
+		}
+	}
+
+	return nil
+}
diff --git a/cty/convert/public_test.go b/cty/convert/public_test.go
index 72ab9830..4300aefa 100644
--- a/cty/convert/public_test.go
+++ b/cty/convert/public_test.go
@@ -249,6 +249,16 @@ func TestConvert(t *testing.T) {
 				cty.StringVal("hello"),
 			}),
 		},
+		{
+			Value: cty.ListValEmpty(cty.String),
+			Type:  cty.Set(cty.DynamicPseudoType),
+			Want:  cty.SetValEmpty(cty.String),
+		},
+		{
+			Value: cty.SetValEmpty(cty.String),
+			Type:  cty.List(cty.DynamicPseudoType),
+			Want:  cty.ListValEmpty(cty.String),
+		},
 		{
 			Value: cty.ObjectVal(map[string]cty.Value{
 				"num": cty.NumberIntVal(5),
@@ -581,6 +591,64 @@ func TestConvert(t *testing.T) {
 			Type: cty.Object(map[string]cty.Type{"foo": cty.String}),
 			Want: cty.ObjectVal(map[string]cty.Value{"foo": cty.StringVal("hello")}),
 		},
+		// reduction of https://github.com/hashicorp/terraform/issues/23804
+		{
+			Value: cty.ObjectVal(map[string]cty.Value{
+				"a": cty.ObjectVal(map[string]cty.Value{
+					"x": cty.TupleVal([]cty.Value{cty.StringVal("foo")}),
+				}),
+				"b": cty.ObjectVal(map[string]cty.Value{
+					"x": cty.TupleVal([]cty.Value{cty.StringVal("bar")}),
+				}),
+				"c": cty.ObjectVal(map[string]cty.Value{
+					"x": cty.TupleVal([]cty.Value{cty.StringVal("foo"), cty.StringVal("bar")}),
+				}),
+			}),
+			Type: cty.Map(cty.Map(cty.DynamicPseudoType)),
+			Want: cty.MapVal(map[string]cty.Value{
+				"a": cty.MapVal(map[string]cty.Value{
+					"x": cty.ListVal([]cty.Value{cty.StringVal("foo")}),
+				}),
+				"b": cty.MapVal(map[string]cty.Value{
+					"x": cty.ListVal([]cty.Value{cty.StringVal("bar")}),
+				}),
+				"c": cty.MapVal(map[string]cty.Value{
+					"x": cty.ListVal([]cty.Value{cty.StringVal("foo"), cty.StringVal("bar")}),
+				}),
+			}),
+		},
+		// reduction of https://github.com/hashicorp/terraform/issues/24167
+		{
+			Value: cty.ObjectVal(map[string]cty.Value{
+				"a": cty.ObjectVal(map[string]cty.Value{
+					"x": cty.NullVal(cty.DynamicPseudoType),
+				}),
+				"b": cty.ObjectVal(map[string]cty.Value{
+					"x": cty.ObjectVal(map[string]cty.Value{
+						"c": cty.NumberIntVal(1),
+						"d": cty.NumberIntVal(2),
+					}),
+				}),
+			}),
+			Type:      cty.Map(cty.Map(cty.Object(map[string]cty.Type{"x": cty.Map(cty.DynamicPseudoType)}))),
+			WantError: true,
+		},
+		// reduction of https://github.com/hashicorp/terraform/issues/23431
+		{
+			Value: cty.ObjectVal(map[string]cty.Value{
+				"a": cty.ObjectVal(map[string]cty.Value{
+					"x": cty.StringVal("foo"),
+				}),
+				"b": cty.MapValEmpty(cty.DynamicPseudoType),
+			}),
+			Type: cty.Map(cty.Map(cty.DynamicPseudoType)),
+			Want: cty.MapVal(map[string]cty.Value{
+				"a": cty.MapVal(map[string]cty.Value{
+					"x": cty.StringVal("foo"),
+				}),
+				"b": cty.MapValEmpty(cty.String),
+			}),
+		},
 	}
 
 	for _, test := range tests {
diff --git a/cty/convert/unify.go b/cty/convert/unify.go
index 53ebbfe0..ee171d1e 100644
--- a/cty/convert/unify.go
+++ b/cty/convert/unify.go
@@ -28,11 +28,14 @@ func unify(types []cty.Type, unsafe bool) (cty.Type, []Conversion) {
 	// a subset of that type, which would be a much less useful conversion for
 	// unification purposes.
 	{
+		mapCt := 0
 		objectCt := 0
 		tupleCt := 0
 		dynamicCt := 0
 		for _, ty := range types {
 			switch {
+			case ty.IsMapType():
+				mapCt++
 			case ty.IsObjectType():
 				objectCt++
 			case ty.IsTupleType():
@@ -44,6 +47,8 @@ func unify(types []cty.Type, unsafe bool) (cty.Type, []Conversion) {
 			}
 		}
 		switch {
+		case mapCt > 0 && (mapCt+dynamicCt) == len(types):
+			return unifyMapTypes(types, unsafe, dynamicCt > 0)
 		case objectCt > 0 && (objectCt+dynamicCt) == len(types):
 			return unifyObjectTypes(types, unsafe, dynamicCt > 0)
 		case tupleCt > 0 && (tupleCt+dynamicCt) == len(types):
@@ -95,6 +100,44 @@ Preferences:
 	return cty.NilType, nil
 }
 
+func unifyMapTypes(types []cty.Type, unsafe bool, hasDynamic bool) (cty.Type, []Conversion) {
+	// If we had any dynamic types in the input here then we can't predict
+	// what path we'll take through here once these become known types, so
+	// we'll conservatively produce DynamicVal for these.
+	if hasDynamic {
+		return unifyAllAsDynamic(types)
+	}
+
+	elemTypes := make([]cty.Type, 0, len(types))
+	for _, ty := range types {
+		elemTypes = append(elemTypes, ty.ElementType())
+	}
+	retElemType, _ := unify(elemTypes, unsafe)
+	if retElemType == cty.NilType {
+		return cty.NilType, nil
+	}
+
+	retTy := cty.Map(retElemType)
+
+	conversions := make([]Conversion, len(types))
+	for i, ty := range types {
+		if ty.Equals(retTy) {
+			continue
+		}
+		if unsafe {
+			conversions[i] = GetConversionUnsafe(ty, retTy)
+		} else {
+			conversions[i] = GetConversion(ty, retTy)
+		}
+		if conversions[i] == nil {
+			// Shouldn't be reachable, since we were able to unify
+			return cty.NilType, nil
+		}
+	}
+
+	return retTy, conversions
+}
+
 func unifyObjectTypes(types []cty.Type, unsafe bool, hasDynamic bool) (cty.Type, []Conversion) {
 	// If we had any dynamic types in the input here then we can't predict
 	// what path we'll take through here once these become known types, so