We examine the extent to which readily available data at a large public university can be used to a priori identify at-risk students who may benefit from targeted retention efforts. Although it is possible to identify such students, there remains an inevitable tradeoff in any resource allocation between not treating the students who are likely to exit without treatment and treating students who are likely not to exit in the absence of the treatment. At-risk students are found to remain at risk throughout their college career. Moreover, conditional on exiting the institution, the degree to which the student was at risk is predictive of whether the student subsequently re-enrolls elsewhere and the type of institution at which this re-enrollment occurs. In this context, we discuss how retention policies relate to insuring the initial match is appropriate, recognizing that some attrition can be in keeping with the broad social interest.