Conversation so far:
What was Bernstein's involvement with social activism?
he was also known for his outspoken political views and his strong desire to further social change.
What issues was he involved with?
His first aspirations for social change were made apparent in his producing (as a student) a recently banned opera, The Cradle Will Rock, by Marc Blitzstein.

Question: What else happened?
Self-contained rewrite: What else happened other than Leonard Bernstein poducing the opera The Cradle Will Rock?