The isolation and structure elucidation of three new β-1actam indole alkaloids, chartellines B and C and methoxydechlorochartelline A, from the marine bryozoan Chartella papyracea are described. The chartellines only differ in the number and position of the bromo substituents. Dechloro-3-methoxychartelline A is an artifact formed during the isolation procedure and is synthesized from chartelline A. All four alkaloids have the S configuration. © 1987, American Chemical Society. All rights reserved.