Cargo cart 10 can be used independently or attached to a conventional walker 101. Cooperative attach means 40 connect cart 10 in front of walker 101 through roll leader 44, which propels and steers cart 10 in response to user's control of walker 101. In attached mode, rear wheels 34 of cart 10 are suspended above travel surface to allow cart 10 to be steered easily and predictably by roll leader 44. Cart 10 is attached and detached with one hand without tools. Handle 50 and optional cargo basket 29 fold flat for storage. Slots in peripheral rails 24 retain cargo that is wider than cargo support 28.