The purpose of this thesis was to examine the knowledge, interest, and use of sport psychology by elite coaches in Thailand and the effect of a psychological skills training program on knowledge, interest, and use. The thesis involved three linked studies, the first investigated initial knowledge, interest, and use, the second examined the effect of a psychological skills training (PST)program, on knowledge, interest, and use with an independent groups design, and the third examined the effect of a PST program on knowledge, interest, and use, based on a repeated measures design.