This chapter illustrates how security forces have evolved since the end of the Cold War. The legacy of professionalization and politicization has made deep and comprehensive security sector reform difficult to achieve. Instead, as illustrated here, governments respond to real or perceived security issues by creating new, and more specialized, forces. This chapter focuses on the creation and proliferation of state security forces across Latin America in the modern era. To illustrate this complexity, we draw from a new dataset that tracks the architecture of state violence by documenting the various tactical, counternarcotic, and border security units that have been created between 1990 and today. We also highlight how the proliferation of new security forces is, in part, due to the continued influence of the United States through ongoing financing and training operations, even during the post-Cold War democratic era. The chapter concludes by discussing challenges associated with these trends; the proliferation of forces makes abuses more likely while simultaneously complicating any efforts toward accountability or reform.