University entrance criteria can be a contentious topic, particularly in respect of equity. In this paper we discuss studies which demonstrate that revisions of entrance criteria which are designed with no explicit reference to equity issues can have a surprisingly positive impact on the fractions of disadvantaged subgroups admitted. We demonstrate this impact in the New Zealand context with special reference to a "dual admission model" that we believe could have broad applicability. An assessment of the variability of the estimates of the impact of changed entry criteria (calculated using a simulation method) demonstrates the statistical significance of our results, thus providing confirmation that the apparent impact is not illusory. (Contains 3 figures and 2 notes.)