This chapter adopts a metascientific perspective and discusses two basic questions: (1) What are criteria for evaluating the quality of a psychological theory? (2) What are criteria for evaluating the empirical evidence related to a theory? The chapter discusses these criteria on a general level and by examining one specific theory and accompanying empirical work as an illustrative example—the Strength Model of Self-Control by Baumeister and colleagues (Baumeister and Heatherton Psychol Inq 7:1–15, 1996; Baumeister and Vohs Adv Exp Soc Psychol 54:67–127, 2016). Although necessarily incomplete, the discussed criteria for the quality of theorizing and empiricism can be applied to many theories in (social) psychological research. They are therefore relevant not only to basic research, but also to any applied work that is grounded in theory.