diff --git a/bin/modify-profile-data.php b/bin/modify-profile-data.php
new file mode 100644
index 0000000..fc55035
--- /dev/null
+++ b/bin/modify-profile-data.php
@@ -0,0 +1,104 @@
+<?php
+
+/*
+ * Modify existing `bpmain_bp_xprofile_data` fields to match new team names, etc.
+ *
+ * Usage: wp eval-file modify-profile-data.php
+ *
+ * @see https://github.com/WordPress/five-for-the-future/issues/83
+ */
+
+namespace WordPressDotOrg\FiveForTheFuture\Bin;
+use WordPressDotOrg\FiveForTheFuture\XProfile;
+use WP_ClI;
+
+wp_debug_mode();    // re-set `display_errors` after WP-CLI overrides it, see https://github.com/wp-cli/wp-cli/issues/706#issuecomment-203610437
+
+/** @var string $file The filename of the current script */
+/** @var array  $args The arguments passed to this script from the command line */
+main( $file, $args );
+
+
+/**
+ * The main controller
+ */
+function main( $file, $args ) {
+	WP_CLI::line();
+
+	WP_CLI::confirm(
+		"Be very careful when using this, as it will modify production data. It should only be run manually after careful review of the code. Take a backup of the db table before running this, in case anything goes wrong. Proceed?"
+	);
+
+	update_chosen_teams();
+
+	WP_CLI::success( 'Done. Please manually check everything to make sure it worked correctly.' );
+}
+
+/**
+ * Make changes to the data the users have saved about their teams.
+ */
+function update_chosen_teams() {
+	global $wpdb;
+
+	$table = 'bpmain_bp_xprofile_data';
+
+	$query = $wpdb->prepare( "
+		SELECT id, value
+		FROM `$table`
+		WHERE field_id = %d",
+		XProfile\FIELD_IDS['team_names']
+	);
+
+	$rows = $wpdb->get_results( $query, ARRAY_A );
+
+	foreach ( $rows as $row ) {
+		$updated      = false;
+		$chosen_teams = (array) maybe_unserialize( $row['value'] );
+
+		if ( empty( $chosen_teams ) ) {
+			continue;
+		}
+
+		$original_team_count = count( $chosen_teams ); // Can't do this in the loop because it would be reduced when team are removed.
+
+		for ( $i = 0; $i < $original_team_count; $i++ ) {
+			/*
+			 * Postfix 'Team' to all team names -- e.g., 'Support' => 'Support Team' -- to make it obvious that
+			 * we're referring to an official Make team, not supporting a private plugin/theme.
+			 */
+			if ( 'Team' !== substr( $chosen_teams[ $i ], -4 ) ) {
+				$updated             = true;
+				$chosen_teams[ $i ] .= ' Team';
+			}
+
+			// Clarify name of Theme Review Team to remove ambiguity.
+			if ( 'Themes Team' === $chosen_teams[ $i ] ) {
+				$updated            = true;
+				$chosen_teams[ $i ] = 'Theme Review Team';
+			}
+
+			// Clarify name of WP-CLI Team to remove ambiguity.
+			if ( 'CLI Team' === $chosen_teams[ $i ] ) {
+				$updated            = true;
+				$chosen_teams[ $i ] = 'WP-CLI Team';
+			}
+
+			// Remove users from closed groups, because the vast majority of them are not actually members.
+			if ( 'Plugins Team' === $chosen_teams[ $i ] || 'Security Team' === $chosen_teams[ $i ] ) {
+				$updated = true;
+				unset( $chosen_teams[ $i ] );
+			}
+		}
+
+		if ( $updated ) {
+			// Reindex the array after `unset()`, otherwise `serialize()` will create blank items.
+			$chosen_teams = array_values( $chosen_teams );
+
+			$wpdb->update(
+				$table,
+				array( 'value' => maybe_serialize( $chosen_teams ) ),
+				array( 'id'    => $row['id'] )
+			);
+		}
+	}
+}