Various scholars stress that traditional regulatory regimes will benefit from greater private sector involvement. There has been little empirical study, however, on the impact of the "amount" of privatization on certain policy goals. This paper aims at filling that knowledge gap. Based on an analysis of private sector involvement in the enforcement of Australian and Canadian building codes, it argues that a certain threshold exists after which more privatization no longer results in effectiveness and efficiency gains. It furthermore discovers that the relationship between the public and private sector within a regime matters in reaching certain policy goals.