The word “theory” means different things to different contemporary criminologists, depending on their philosophies about the nature of criminology, what it is attempting to accomplish, and how they think criminology ought to be done. Diversity is evident from the presence of at least seven differing “philosophies of the enterprise,” expressed in distinct “models” for doing criminology. The seven approaches include: (1) theoretical science; (2) problem solving; (3) “verstehen” analysis; (4) descriptive approaches; (5) critical work; (6) nihilistic thinking; and (7) amelioration. Yet, there does appear to be a dominant paradigm. In the following pages, I will briefly describe six of the styles of contemporary criminology and assess the meaning and importance of theory in each. However, my description of theoretical science is far more extensive than it is for the other six because theoretical science seems to be the most widely endorsed, even if not always actually practiced, mode of work in contemporary criminology. While all seven of the models to be discussed have an established place in the criminological landscape, are represented by strong advocates, contain powerful intellectual challenges, have produced important results, and command a degree of influence, most criminology seems to follow, to one degree or another, the model of science. Of course, classifying scholars and/or their products into camps is always somewhat arbitrary, and the relative popularity of the various modes of work may be undergoing change. Nevertheless, for now I will follow the classification scheme outlined above in trying to describe theory and its uses in contemporary criminology.