Major oil and gas companies are shifting their exploration and production (E and P) investment from the United Stares to foreign countries. As they do so, smaller companies, ＇＇independents,＇＇ are expected to play a more prominent role in domestic E and P. Within bath industry and government circles the apprehension is widespread that such a shift from the majors to the independents will cause domestic oil and gas resources to be developed less aggressively and less efficiently. This paper attempts to discern and quantify differences in firm behavior and success among firms of different sizes (majors, large and small independents) operating on the Gulf of Mexico OCS region. Contrary to conventional thinking, descriptive analysis of data on drilling effort and outcomes on the Gulf of Mexico indicates independents have been both more aggressive and successful than the majors in exploration while the majors have been only moderately more successful than independents in development drilling.