Scorsese initially named the film Wise Guy, but postponed it, and later he and Pileggi changed the name to Goodfellas. To prepare for their roles in the film, Robert De Niro, Joe Pesci, and Ray Liotta often spoke with Pileggi, who shared research material left over from writing the book. According to Pesci, improvisation and ad-libbing came out of rehearsals where Scorsese gave the actors freedom to do whatever they wanted. The director made transcripts of these sessions, took the lines he liked best, and put them into a revised script the cast worked from during principal photography.