This chapter explains the role expansion inherent in the "new professionalism" both eased the Peruvian military's initial assumption of political power, and complicated its retreat from it. Like many important ideas in the social sciences, it has been defined in various ways. Alfred Stepan, one of the most able contemporary scholars of Latin American military politics, has observed that the "new" professionalism focuses upon internal security and national development; the "old" professionalism centers on external defense. "New professionalism" echoed through other Latin American countries as well. The outlooks of the "new professionalism" were added to the major responsibilities the Peruvian military already shouldered under the laws and customs of the country when elections neared. Stepan demonstrated his contentions through content analysis of over 1,000 articles in Peruvian military journals. Peruvian society itself was differentially affected by economic development and social mobilization.