This chapter points at routines as drivers of organizational behavior. It offers a typology of organizational behavior that comprises five types: simple routines, complex routines, adaptation, improvisation, and innovation. Examining simple and complex routines, the chapter provides a definition of routines and examples, and underlines the advantages of the concept of routine vis-à-vis the concept of organizational culture. The chapter then examines the functions of routines, showing that routines have in-built flexibility that allows actors (varying degrees) of discretion. In a further step, mechanisms are discussed that spur the reproduction of routines. For military organizations, these are formal rules, training and education, and artifacts. Following this, the chapter argues that while routines can change, the stickiness of routines makes changes to routines, and to organizations more generally, difficult. In this context, adaptation, improvisation, and innovation are presented as forms of non-routine behavior. In a last step, the chapter shows how organizational routines impact the organizational environment.