diff --git a/command/013_config_upgrade.go b/command/013_config_upgrade.go
index 997f44f77..890752384 100644
--- a/command/013_config_upgrade.go
+++ b/command/013_config_upgrade.go
@@ -30,7 +30,11 @@ const skippedConfigurationFileWarning = "The %s configuration file %q was skippe
 
 func (c *ZeroThirteenUpgradeCommand) Run(args []string) int {
 	args = c.Meta.process(args)
+
+	var skipConfirm bool
+
 	flags := c.Meta.defaultFlagSet("0.13upgrade")
+	flags.BoolVar(&skipConfirm, "yes", false, "skip confirmation prompt")
 	flags.Usage = func() { c.Ui.Error(c.Help()) }
 	if err := flags.Parse(args); err != nil {
 		return 1
@@ -104,7 +108,7 @@ func (c *ZeroThirteenUpgradeCommand) Run(args []string) int {
 		if strings.HasSuffix(strings.ToLower(path), ".json") {
 			diags = diags.Append(tfdiags.Sourceless(
 				tfdiags.Warning,
-				"JSON configuration file was not rewritten",
+				"JSON configuration file ignored",
 				fmt.Sprintf(
 					skippedConfigurationFileWarning,
 					"JSON",
@@ -126,12 +130,44 @@ func (c *ZeroThirteenUpgradeCommand) Run(args []string) int {
 		return 1
 	}
 
+	// Explain what the command does and how to use it, and ask for confirmation.
+	if !skipConfirm {
+		c.Ui.Output(fmt.Sprintf(`
+This command will update the configuration files in the given directory to use
+the new provider source features from Terraform v0.13. It will also highlight
+any providers for which the source cannot be detected, and advise how to
+proceed.
+
+We recommend using this command in a clean version control work tree, so that
+you can easily see the proposed changes as a diff against the latest commit.
+If you have uncommited changes already present, we recommend aborting this
+command and dealing with them before running this command again.
+`))
+
+		query := "Would you like to upgrade the module in the current directory?"
+		if dir != "." {
+			query = fmt.Sprintf("Would you like to upgrade the module in %s?", dir)
+		}
+		v, err := c.Ui.Ask(query)
+		if err != nil {
+			diags = diags.Append(err)
+			c.showDiagnostics(diags)
+			return 1
+		}
+		if v != "yes" {
+			c.Ui.Info("Upgrade cancelled.")
+			return 0
+		}
+
+		c.Ui.Output(`-----------------------------------------------------------------------------`)
+	}
+
 	// It's not clear what the correct behaviour is for upgrading override
 	// files. For now, just log that we're ignoring the file.
 	for _, path := range overrides {
 		diags = diags.Append(tfdiags.Sourceless(
 			tfdiags.Warning,
-			"Override configuration file was not rewritten",
+			"Override configuration file ignored",
 			fmt.Sprintf(
 				skippedConfigurationFileWarning,
 				"override",
diff --git a/command/013_config_upgrade_test.go b/command/013_config_upgrade_test.go
index d0a7fa23f..195c30a78 100644
--- a/command/013_config_upgrade_test.go
+++ b/command/013_config_upgrade_test.go
@@ -1,6 +1,7 @@
 package command
 
 import (
+	"bytes"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -123,7 +124,7 @@ func TestZeroThirteenUpgrade_success(t *testing.T) {
 				},
 			}
 
-			if code := c.Run(nil); code != 0 {
+			if code := c.Run([]string{"-yes"}); code != 0 {
 				t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
 			}
 
@@ -173,7 +174,7 @@ func TestZeroThirteenUpgrade_submodule(t *testing.T) {
 	}
 
 	// Here we pass a target module directory to process
-	if code := c.Run([]string{"module"}); code != 0 {
+	if code := c.Run([]string{"-yes", "module"}); code != 0 {
 		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
 	}
 
@@ -203,7 +204,7 @@ func TestZeroThirteenUpgrade_skippedFiles(t *testing.T) {
 		},
 	}
 
-	if code := c.Run(nil); code != 0 {
+	if code := c.Run([]string{"-yes"}); code != 0 {
 		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
 	}
 
@@ -221,6 +222,67 @@ func TestZeroThirteenUpgrade_skippedFiles(t *testing.T) {
 	}
 }
 
+func TestZeroThirteenUpgrade_confirm(t *testing.T) {
+	inputPath := testFixturePath(path.Join("013upgrade-explicit-providers", "input"))
+
+	td := tempDir(t)
+	copy.CopyDir(inputPath, td)
+	defer os.RemoveAll(td)
+	defer testChdir(t, td)()
+
+	ui := new(cli.MockUi)
+	inputBuf := &bytes.Buffer{}
+	ui.InputReader = inputBuf
+	inputBuf.WriteString("yes")
+	c := &ZeroThirteenUpgradeCommand{
+		Meta: Meta{
+			testingOverrides: metaOverridesForProvider(testProvider()),
+			Ui:               ui,
+		},
+	}
+
+	if code := c.Run(nil); code != 0 {
+		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
+	}
+
+	output := ui.OutputWriter.String()
+	if !strings.Contains(output, "Upgrade complete") {
+		t.Fatal("unexpected output:", output)
+	}
+}
+
+func TestZeroThirteenUpgrade_cancel(t *testing.T) {
+	inputPath := testFixturePath(path.Join("013upgrade-explicit-providers", "input"))
+
+	td := tempDir(t)
+	copy.CopyDir(inputPath, td)
+	defer os.RemoveAll(td)
+	defer testChdir(t, td)()
+
+	ui := new(cli.MockUi)
+	inputBuf := &bytes.Buffer{}
+	ui.InputReader = inputBuf
+	inputBuf.WriteString("no")
+	c := &ZeroThirteenUpgradeCommand{
+		Meta: Meta{
+			testingOverrides: metaOverridesForProvider(testProvider()),
+			Ui:               ui,
+		},
+	}
+
+	if code := c.Run(nil); code != 0 {
+		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
+	}
+
+	output := ui.OutputWriter.String()
+	if !strings.Contains(output, "Upgrade cancelled") {
+		t.Fatal("unexpected output:", output)
+	}
+	if strings.Contains(output, "Upgrade complete") {
+		t.Fatal("unexpected output:", output)
+	}
+}
+
 func TestZeroThirteenUpgrade_unsupportedVersion(t *testing.T) {
 	inputPath := testFixturePath("013upgrade-unsupported-version")
 
@@ -237,7 +299,7 @@ func TestZeroThirteenUpgrade_unsupportedVersion(t *testing.T) {
 		},
 	}
 
-	if code := c.Run(nil); code == 0 {
+	if code := c.Run([]string{"-yes"}); code == 0 {
 		t.Fatal("expected error, got:", ui.OutputWriter)
 	}
 
@@ -309,7 +371,7 @@ func TestZeroThirteenUpgrade_empty(t *testing.T) {
 		},
 	}
 
-	if code := c.Run(nil); code == 0 {
+	if code := c.Run([]string{"-yes"}); code == 0 {
 		t.Fatal("expected error, got:", ui.OutputWriter)
 	}