This research explores the relative influence of salespeople's attitudes toward selling a new product, perceptions of subjective norms, and self-efficacy on the development of selling intentions and, ultimately, the success of a new product launch. The longitudinal study employs a nonlinear growth curve model that leverages survey data from industrial salespeople and objective performance records of their daily sales during the first several months in the market of two new products: a new-to-market product and a line extension. By examining salesperson-level variance on new product performance, the authors suggest that managers should focus on increasing salesperson self-efficacy and positive attitudes toward selling the product to build selling intentions and quickly grow new product performance. They also suggest that sales managers should resist the temptation to rely on normative pressure during a new product introduction. Not only are subjective norms less effective in building selling intentions, but they also diminish the positive impact of attitudes and self-efficacy on salesperson intentions and constrain the positive relationships between intentions and performance and self-efficacy and performance.