One of the central questions in marketing is whether targeted training of salespeople can actually lead to increased sales. According to business rationality, such training ultimately represents an investment in human capital and should therefore yield a positive result for the company when viewed from a cost-benefit perspective. Against this background, it is all the more surprising that there are hardly any studies that actually investigate the effectiveness of such training. This is precisely where the author comes in. The present volume deals with a matter that is significant both theoretically and practically, namely the increase in sales through sales psychology and how this could be conceptually measured.