An adoption model was proposed to examine the influence of four types of organizational factors- organizational capacity, organizational structure, operating environment and grantmaking orientation- on the adoption of four effectiveness best practices, formal evaluation, knowledge management, leadership development and operating grants in philanthropic foundations. Data were collected from a national survey of foundations and the Foundation Center database. The results indicate that the grantmaking orientation of a foundation is the greatest indicator of adoptive behavior. Furthermore, capacity constraints are most relevant to the adoption decision when the adopting practice requires significant investments of time, money and expertise. Given the social and political context in which the effectiveness best practices are associated, this dissertation research has broad relevance for the ways in which foundation behavior is perceived and the means by which that behavior is shaped through policy and practice.