We show that the strength of the corporate governance system depends on both firm characteristics and the composition of the outsiders' overall portfolio. A strong governance system is optimal when the value of the firm?s assets in place, relative to the growth opportunity, is sufficiently small or is sufficiently large, suggesting a corporate governance life cycle. In addition, more diversified outsiders (such as generalist mutual funds) prefer stronger governance, while outsiders with a portfolio heavily invested in the same asset class as the firm (such as venture capitalists or private equity investors) are more willing to tolerate a weak governance system, where the portfolio companies' insiders have more leeway in determining corporate policies. Finally, we find that ambiguity aversion introduces a direct link between the strength of the corporate governance system and firm transparency, whereby firms with weaker governance should also optimally be more opaque.