Sales researchers have spent decades developing and empirically testing various scales that reflect distinct theoretical perspectives of salesperson behavior and job functioning. Despite extensive research in this area, little comparative work has been done to assess the relative effectiveness of these different scales in explaining salesperson performance or to explicate whether or not they are best considered in isolation or as working together—even potentially interacting—to influence sales success. We examine four established scales related to customer-directed salesperson job functioning, and look at how well they relate to both self-reported and objective job performance measures. Our analyses are based on responses from 524 salespeople drawn from three different firms. The results show that two scales (ADAPTS, Selling Skills) outperform the others. Furthermore, we find an important interaction between ADAPTS and Selling Skills that helps to predict superior objective performance.