After the attack on Pearl Harbor and the U.S. entrance into World War II, the CPTP changed forever, including the name. The Civilian Pilot Training Program became the War Training Service (WTS) and, from 1942 to 1944, served primarily as the screening program for potential pilot candidates. Students still attended classes at colleges and universities and flight training was still conducted by private flight schools, but all WTS graduates were required to sign a contract agreeing to enter the military following graduation. There is a list of colleges and universities participating in the CPTP in '43-'44 in the appendix of "They Flew Proud".