Previous scholarship on congressional elections has identified the amount of campaign funds raised as a key predictor of a candidate’s success on Election Day. But the actual spending of these funds, and the manner and strategy by which candidates do so, has gone understudied largely due to data limitations. In this paper, we parse transaction-level data on House campaign expenditures provided by the Federal Election Commission to investigate specific ways in which House challengers can gain leverage over incumbents and increase their chances of success on Election Day. We find strong evidence that challengers fare far better electorally not simply by spending more money, but also when their spending decisions mirror those of their incumbent opponent on three mostly-unaddressed characteristics: the timing of candidate spending; how much candidates spend in the geographic confines of the district; and what they spend the money on. Based on these characteristics, we create an index of ‘spending likeness’ between challengers and incumbents and find that challengers who reflect the spending habits of their incumbents are able to improve their electoral margins, even after controlling for important electoral features such as differences in total spending amounts, district and national partisan competition, and challenger quality. Our results suggest that nuanced spending choices play a key role in predicting the electoral success by both challengers and incumbents in congressional elections.