Using a sample of 192 Standard & Poor’s 500 firms, we examine the impact of corporate governance and ownership context on a particular instance of board entrenchment: adoption of classified board provisions. Interestingly, while increased outsider representation measured simply as a proportion of outsiders does not affect the rate of adoption, reliance on a more fine grained measure, which includes other affiliations of outsiders, results in a marginally significant influence. Moreover, it appears that reliance on a simple proportional measure is likely to distort the effects of other variables. Finally, institutional stock ownership is found to be the most significant factor associated with decreased rate of adoption.