diff --git a/command/format/diagnostic.go b/command/format/diagnostic.go
new file mode 100644
index 0000000000..4c5f7fff08
--- /dev/null
+++ b/command/format/diagnostic.go
@@ -0,0 +1,65 @@
+package format
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/hashicorp/terraform/tfdiags"
+	"github.com/mitchellh/colorstring"
+	wordwrap "github.com/mitchellh/go-wordwrap"
+)
+
+// Diagnostic formats a single diagnostic message.
+//
+// The width argument specifies at what column the diagnostic messages will
+// be wrapped. If set to zero, messages will not be wrapped by this function
+// at all. Although the long-form text parts of the message are wrapped,
+// not all aspects of the message are guaranteed to fit within the specified
+// terminal width.
+func Diagnostic(diag tfdiags.Diagnostic, color *colorstring.Colorize, width int) string {
+	if diag == nil {
+		// No good reason to pass a nil diagnostic in here...
+		return ""
+	}
+
+	var buf bytes.Buffer
+
+	switch diag.Severity() {
+	case tfdiags.Error:
+		buf.WriteString(color.Color("\n[bold][red]Error: [reset]"))
+	case tfdiags.Warning:
+		buf.WriteString(color.Color("\n[bold][yellow]Warning: [reset]"))
+	default:
+		// Clear out any coloring that might be applied by Terraform's UI helper,
+		// so our result is not context-sensitive.
+		buf.WriteString(color.Color("\n[reset]"))
+	}
+
+	desc := diag.Description()
+	sourceRefs := diag.Source()
+
+	// We don't wrap the summary, since we expect it to be terse, and since
+	// this is where we put the text of a native Go error it may not always
+	// be pure text that lends itself well to word-wrapping.
+	if sourceRefs.Subject != nil {
+		fmt.Fprintf(&buf, color.Color("[bold]%s[reset] at %s\n\n"), desc.Summary, sourceRefs.Subject.StartString())
+	} else {
+		fmt.Fprintf(&buf, color.Color("[bold]%s[reset]\n\n"), desc.Summary)
+	}
+
+	// TODO: also print out the relevant snippet of config source with the
+	// relevant section highlighted, so the user doesn't need to manually
+	// correlate back to config. Before we can do this, the HCL2 parser
+	// needs to be more deeply integrated so that we can use it to obtain
+	// the parsed source code and AST.
+
+	if desc.Detail != "" {
+		detail := desc.Detail
+		if width != 0 {
+			detail = wordwrap.WrapString(detail, uint(width))
+		}
+		fmt.Fprintf(&buf, "%s\n", detail)
+	}
+
+	return buf.String()
+}
diff --git a/command/meta.go b/command/meta.go
index 4412929c78..806bd39615 100644
--- a/command/meta.go
+++ b/command/meta.go
@@ -19,11 +19,13 @@ import (
 	"github.com/hashicorp/go-getter"
 	"github.com/hashicorp/terraform/backend"
 	"github.com/hashicorp/terraform/backend/local"
+	"github.com/hashicorp/terraform/command/format"
 	"github.com/hashicorp/terraform/config"
 	"github.com/hashicorp/terraform/helper/experiment"
 	"github.com/hashicorp/terraform/helper/variables"
 	"github.com/hashicorp/terraform/helper/wrappedstreams"
 	"github.com/hashicorp/terraform/terraform"
+	"github.com/hashicorp/terraform/tfdiags"
 	"github.com/mitchellh/cli"
 	"github.com/mitchellh/colorstring"
 )
@@ -476,6 +478,36 @@ func (m *Meta) confirm(opts *terraform.InputOpts) (bool, error) {
 	}
 }
 
+// showDiagnostics displays error and warning messages in the UI.
+//
+// "Diagnostics" here means the Diagnostics type from the tfdiag package,
+// though as a convenience this function accepts anything that could be
+// passed to the "Append" method on that type, converting it to Diagnostics
+// before displaying it.
+//
+// Internally this function uses Diagnostics.Append, and so it will panic
+// if given unsupported value types, just as Append does.
+func (m *Meta) showDiagnostics(vals ...interface{}) {
+	var diags tfdiags.Diagnostics
+	diags = diags.Append(vals...)
+
+	for _, diag := range diags {
+		// TODO: Actually measure the terminal width and pass it here.
+		// For now, we don't have easy access to the writer that
+		// ui.Error (etc) are writing to and thus can't interrogate
+		// to see if it's a terminal and what size it is.
+		msg := format.Diagnostic(diag, m.Colorize(), 78)
+		switch diag.Severity() {
+		case tfdiags.Error:
+			m.Ui.Error(msg)
+		case tfdiags.Warning:
+			m.Ui.Warn(msg)
+		default:
+			m.Ui.Output(msg)
+		}
+	}
+}
+
 const (
 	// ModuleDepthDefault is the default value for
 	// module depth, which can be overridden by flag