The basic notion of relationship marketing entails that firms should strive for mutually beneficial customer relationships. By combining relationship marketing theory and operations research methods, this paper aims to develop and demonstrate a managerial decision-making model that business market managers can use to optimize and evaluate marketing investments in both a customer-oriented and economically feasible manner. The intended contributions of our work are as follows. First, we add to the return on marketing literature by providing a first decision-making approach that explicitly assesses the optimization of marketing investments in terms of profitability, effort, and resource allocation. Second, we show how the risk of marketing investments can be assessed using sensitivity analysis. By means of an empirical study the versatility of our decision-making approach is demonstrated by assessing various critical decision making issues for business marketing managers in detail.