This paper reviews social psychological measures that might usefully be employed within sociological treatments of human agency. Sociologists have engaged both (a) the structural constraints and opportunities that channel individual action and (b) the subjective sense individuals develop reflecting beliefs about their ability to affect those structures and their life courses. We briefly spell out the well-trod agency vs. structure debate before exploring six concepts that have or could be used in organizing and theorizing empirical research on the subjective version of agency: self-efficacy, locus of control, personal control, mastery, planful competence, and ego-depletion/self-control. For each concept, we provide brief descriptions and representative findings. Taking a life course perspective, we briefly sketch out a series of concerns that scholars engaging in the agency concept should take into account.