Although a large number of studies have been published up to now on peer review in science, only few of them employ a theory-guided approach. Most of the studies fail to connect the empirical findings to theory. The few available theory-guided empirical studies are found predominantly in the older peer review research, which was strongly influenced by the more traditional sociologists of science, referred to as the Mertonians, or the “North American school” of Robert K. Merton. The aim of the present contribution is to present a theoretical framework that includes also recent theory developments and that can serve as a basis for future empirical research on peer review. To do this, peer review is examined from the points of view of the three most important theoretical directions in the sociology of science: (1) the North American school, (2) social constructivism, and (3) social systems theory.