The present study (N = 844) examined the predictive validity and fairness of the assessment center (AC) and the general mental ability (GMA) test used to select officers for the Swiss army. Concerning predictive validity, we found that both selection methods predicted candidates’ academic and military performance at the end of their officer training. Furthermore, the AC had incremental validity beyond GMA, meaning that it cannot be replaced by the GMA test. Concerning the fairness of the selection methods, no significant performance differences were found between candidates from the different Swiss language regions. With one exception, no evidence for differential prediction was found, and for the single exception, the selection procedure used was not the source of the differential prediction. Thus, the AC and the GMA test were generally equally predictive for candidates from the German-speaking region and from the two other language regions. Taken together, the present study attests to the good predictive validity and fairness of the methods used to select officers.