diff --git a/pkg/util/validation/stack.go b/pkg/util/validation/stack.go
index 51efa70dd..230d96291 100644
--- a/pkg/util/validation/stack.go
+++ b/pkg/util/validation/stack.go
@@ -31,17 +31,32 @@ func validateStackName(s string) error {
 	return errors.New("a stack name may only contain alphanumeric, hyphens, underscores, or periods")
 }
 
+// validateStackTagName checks if s is a valid stack tag name, otherwise returns a descriptive error.
+// This should match the stack naming rules enforced by the Pulumi Service.
+func validateStackTagName(s string) error {
+	const maxTagName = 40
+
+	if len(s) == 0 {
+		return errors.Errorf("invalid stack tag %q", s)
+	}
+	if len(s) > maxTagName {
+		return errors.Errorf("stack tag %q is too long (max length %d characters)", s, maxTagName)
+	}
+
+	var tagNameRE = regexp.MustCompile("^[a-zA-Z0-9-_.:]{1,40}$")
+	if tagNameRE.MatchString(s) {
+		return nil
+	}
+	return errors.New("stack tag names may only contain alphanumerics, hyphens, underscores, periods, or colons")
+}
+
 // ValidateStackTags validates the tag names and values.
 func ValidateStackTags(tags map[apitype.StackTagName]string) error {
-	const maxTagName = 40
 	const maxTagValue = 256
 
 	for t, v := range tags {
-		if len(t) == 0 {
-			return errors.Errorf("invalid stack tag %q", t)
-		}
-		if len(t) > maxTagName {
-			return errors.Errorf("stack tag %q is too long (max length %d characters)", t, maxTagName)
+		if err := validateStackTagName(t); err != nil {
+			return err
 		}
 		if len(v) > maxTagValue {
 			return errors.Errorf("stack tag %q value is too long (max length %d characters)", t, maxTagValue)
@@ -59,7 +74,7 @@ func ValidateStackProperties(stack string, tags map[apitype.StackTagName]string)
 		return errors.Errorf("stack name too long (max length %d characters)", maxStackName)
 	}
 	if err := validateStackName(stack); err != nil {
-		return errors.Wrapf(err, "invalid stack name")
+		return err
 	}
 
 	// Ensure tag values won't be rejected by the Pulumi Service. We do not validate that their
diff --git a/pkg/util/validation/stack_test.go b/pkg/util/validation/stack_test.go
new file mode 100644
index 000000000..9a5c5a2b3
--- /dev/null
+++ b/pkg/util/validation/stack_test.go
@@ -0,0 +1,79 @@
+package validation
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/pulumi/pulumi/pkg/apitype"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestValidateStackTag(t *testing.T) {
+	t.Run("valid tags", func(t *testing.T) {
+		names := []string{
+			"tag-name",
+			"-",
+			"..",
+			"foo:bar:baz",
+			"__underscores__",
+			"AaBb123",
+		}
+
+		for _, name := range names {
+			t.Run(name, func(t *testing.T) {
+				tags := map[apitype.StackTagName]string{
+					name: "tag-value",
+				}
+
+				err := ValidateStackTags(tags)
+				assert.NoError(t, err)
+			})
+		}
+	})
+
+	t.Run("invalid stack tag names", func(t *testing.T) {
+		var names = []string{
+			"tag!",
+			"something with spaces",
+			"escape\nsequences\there",
+			"😄",
+			"foo***bar",
+		}
+
+		for _, name := range names {
+			t.Run(name, func(t *testing.T) {
+				tags := map[apitype.StackTagName]string{
+					name: "tag-value",
+				}
+
+				err := ValidateStackTags(tags)
+				assert.Error(t, err)
+				msg := "stack tag names may only contain alphanumerics, hyphens, underscores, periods, or colons"
+				assert.Equal(t, err.Error(), msg)
+			})
+		}
+	})
+
+	t.Run("too long tag name", func(t *testing.T) {
+		tags := map[apitype.StackTagName]string{
+			strings.Repeat("v", 41): "tag-value",
+		}
+
+		err := ValidateStackTags(tags)
+		assert.Error(t, err)
+		msg := fmt.Sprintf("stack tag %q is too long (max length %d characters)", strings.Repeat("v", 41), 40)
+		assert.Equal(t, err.Error(), msg)
+	})
+
+	t.Run("too long tag value", func(t *testing.T) {
+		tags := map[apitype.StackTagName]string{
+			"tag-name": strings.Repeat("v", 257),
+		}
+
+		err := ValidateStackTags(tags)
+		assert.Error(t, err)
+		msg := fmt.Sprintf("stack tag %q value is too long (max length %d characters)", "tag-name", 256)
+		assert.Equal(t, err.Error(), msg)
+	})
+}