An employer who adopts a facially neutral employment practice that disqualifies a larger proportion of protected-class applicants than others is liable under a disparate impact theory. Defendants can escape liability if they show that the practice is justified by business necessity. But demonstrating business necessity requires costly validation studies that themselves impose a significant burden on defendants-upwards of $100,000 according to some estimates. This Article argues that an employer should have a defense against disparate impact liability if it can show that protected-class applicants failed to make reasonable efforts to train or prepare for a job related test. That is, I propose that when plaintiffs contribute to a disparity in this way, the employer should not be liable. I demonstrate that the "lack of effort" defense is consistent with the text of Title VII and the case law, which has largely ignored this issue. Finally, I show that my proposal is supported by both the theoretical rationales underlying disparate impact and a consequentialist analysis.