In medium bowl, mix refried beans and salsa. On 12- or 13-inch serving plate or pizza pan, spread bean mixture in thin layer.
Spread sour cream over bean mixture, leaving about 1-inch border of beans around edge. Spread guacamole over sour cream, leaving border of sour cream showing.
Sprinkle cheese over guacamole. Sprinkle onions over cheese. Serve immediately, or cover and refrigerate until serving. Serve with tortilla chips.