Data envelopment analysis is used to analyze the efficiency of candidate campaign spending. Analysis of the measured efficiency scores of the incumbents and challengers shows that there are significant systematic effects of both district and candidate characteristics. The incumbent's residuals from the efficiency score regressions indicate those candidates who do well because of the nature of their district and those who do well because of their own abilities. Incumbents are ranked according to their observed efficiency, their unobserved efficiency and their vote share. Correlations among the rankings are significant and of the expected signs. More efficient candidates receive higher vote shares.