This chapter discusses how the proven effectiveness of HF resulted in its widespread dissemination. Those opting for a faithful replication of PHF usually sought direct advice and consultation from Tsemberis. Pathways to Housing in New York also expanded to other cities. Spinoff programs, begun at Pathways to Housing’s instigation and having a shared governance structure, were founded in Washington DC, Philadelphia, and Vermont. Yet as more programs emerged, identifying what was and was not a “HF program” became increasingly difficult, which motivated the publication of a HF manual and fidelity metric. Within this chapter, domestic variants of PHF and other versions of HF are described using an implementation science framework.