This paper expands the model of rational action by introducing a new concept. rational laziness, to better understand actors’ decision making. In addition to rational information processing, human beings often rely on automatic and lion-cognitive mental capacities, and I use the term mental laziness to account for information processing based on these capacities. When time is limited, supply abundant, and decisions have to be made, mental laziness might be a rational decision device. Actors’ choice of rational-calculating or automatic-spontaneous mental decision devices is contingent on their locations within an opportunity structure. The empirical case studied is employers’ hiring processes, and employers’ activation of these action generating mechanisms are expected to cause discrimination of job applicants categorized as out-groups members.