Conversation so far:
What is David Rockefeller's CFR?
David Rockefeller had a lifelong association with the Council on Foreign Relations when he joined as a director.
Did David Rockefeller found more than one non-profit?
David Rockefeller has founded non-profits International Executive Service Corps, and the Partnership for New York City.

Question: When did he become the director of CFR?
Self-contained rewrite: When did David Rockefeller become the director of the Council on Foreign Relations?