diff --git a/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/modifiers.kt b/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/modifiers.kt
index 3e99464ee5..3a1e39624b 100644
--- a/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/modifiers.kt
+++ b/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/modifiers.kt
@@ -46,7 +46,7 @@ public data class Shrink(
 /**
  * Add additional space around the item.
  */
-@Modifier(3, RowScope::class, ColumnScope::class)
+@Modifier(3, RowScope::class, ColumnScope::class, BoxScope::class)
 public data class Margin(
   val margin: app.cash.redwood.ui.Margin,
 )
@@ -54,7 +54,7 @@ public data class Margin(
 /**
  * Set the alignment for an item along the horizontal axis.
  */
-@Modifier(4, ColumnScope::class)
+@Modifier(4, ColumnScope::class, BoxScope::class)
 public data class HorizontalAlignment(
   val alignment: CrossAxisAlignment,
 )
@@ -62,7 +62,7 @@ public data class HorizontalAlignment(
 /**
  * Set the alignment for an item along the vertical axis.
  */
-@Modifier(5, RowScope::class)
+@Modifier(5, RowScope::class, BoxScope::class)
 public data class VerticalAlignment(
   val alignment: CrossAxisAlignment,
 )
@@ -70,7 +70,7 @@ public data class VerticalAlignment(
 /**
  * Set a required width for an item.
  */
-@Modifier(6, RowScope::class, ColumnScope::class)
+@Modifier(6, RowScope::class, ColumnScope::class, BoxScope::class)
 public data class Width(
   val width: Dp,
 )
@@ -78,7 +78,7 @@ public data class Width(
 /**
  * Set a required height for an item.
  */
-@Modifier(7, RowScope::class, ColumnScope::class)
+@Modifier(7, RowScope::class, ColumnScope::class, BoxScope::class)
 public data class Height(
   val height: Dp,
 )
@@ -86,7 +86,7 @@ public data class Height(
 /**
  * Set a required width and height for an item.
  */
-@Modifier(8, RowScope::class, ColumnScope::class)
+@Modifier(8, RowScope::class, ColumnScope::class, BoxScope::class)
 public data class Size(
   val width: Dp,
   val height: Dp,
diff --git a/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/schema.kt b/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/schema.kt
index 035e8e6b1f..1e100e5742 100644
--- a/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/schema.kt
+++ b/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/schema.kt
@@ -19,17 +19,23 @@ import app.cash.redwood.schema.Schema
 
 @Schema(
   [
-    Row::class,
+    // Widgets
+    Box::class,
     Column::class,
+    Row::class,
     Spacer::class,
+    // Next tag: 5
+
+    // Modifiers
     Grow::class,
-    Shrink::class,
-    Margin::class,
+    Height::class,
     HorizontalAlignment::class,
+    Margin::class,
+    Shrink::class,
+    Size::class,
     VerticalAlignment::class,
     Width::class,
-    Height::class,
-    Size::class,
+    // Next tag: 9
   ],
 )
 public interface RedwoodLayout
diff --git a/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/widgets.kt b/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/widgets.kt
index d8868e4a88..7a37dd3f36 100644
--- a/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/widgets.kt
+++ b/redwood-layout-schema/src/main/kotlin/app/cash/redwood/layout/widgets.kt
@@ -169,3 +169,59 @@ public data class Spacer(
   @Default("Dp(0.0)")
   val height: Dp,
 )
+
+/**
+ * Lays out widgets along the z-axis in a column.
+ *
+ * Minimum and maximum heights do not include margins.
+ */
+@Widget(4)
+public data class Box(
+  /**
+   * Sets whether the box's width will match its widest child ([Constraint.Wrap]) or match the width
+   * of its parent ([Constraint.Fill]).
+   */
+  @Property(1)
+  @Default("Constraint.Wrap")
+  val width: Constraint,
+
+  @Property(2)
+  @Default("Dp(0.0)")
+  val minWidth: Dp,
+
+  @Property(3)
+  @Default("Dp(Double.MAX_VALUE)")
+  val maxWidth: Dp,
+
+  /**
+   * Sets whether the box's height will match its tallest child ([Constraint.Wrap]) or match the
+   * height of its parent ([Constraint.Fill]).
+   */
+  @Property(4)
+  @Default("Constraint.Wrap")
+  val height: Constraint,
+
+  @Property(5)
+  @Default("Dp(0.0)")
+  val minHeight: Dp,
+
+  @Property(6)
+  @Default("Dp(Double.MAX_VALUE)")
+  val maxHeight: Dp,
+
+  /**
+   * Applies margin (space) around the box.
+   *
+   * This can also be applied to an individual widget using `Modifier.margin`.
+   */
+  @Property(7)
+  @Default("Margin.Zero")
+  val margin: Margin,
+
+  /**
+   * A slot to add widgets in.
+   */
+  @Children(1) val children: BoxScope.() -> Unit,
+)
+
+public object BoxScope