This article presents findings from a critical review of 163 peer-reviewed articles on the growth of private higher education (HE) cross-nationally. Our review finds that the vast majority of studies on the development of private HE are country-specific case studies, with few comparative or cross-national studies. Moreover, most studies endorse a set of simple causal storylines about the growth of private HE that positions it as a straightforward "solution" to "problems," with private HE most frequently framed as either demand-absorbing or quality-enhancing. To advance more nuanced explanations, our review identified 18 factors--four supranational and 14 national--that influence the growth of private HE. We develop a conceptual model that highlights the diverse actors and processes involved. In concluding, we call for more cross-national and comparative studies on private HE that can better theorize the relative impact of specific factors on the sector.