An extensive body of literature documents that positioning is a central success factor for the launch and overall performance of new products in the marketplace. Under certain circumstances, however, the measurement of positioning success can be problematic. Specifically, the application of attribute-based measurement methods, which are frequently used in practice for this purpose, is subject to limitations in certain situations. For example, these methods can be problematic in product categories where products are evaluated as a whole or where they even lack attributes that create valuable differentiation. Their application can also be difficult in product markets in which the importance of product attributes is constantly shifting or in a cross-national context where the importance of various attributes is likely to differ across countries. This paper introduces a new approach for measuring positioning effectiveness that helps overcome some key limitations of extant approaches and serves as a support tool for positioning-related decisions. Positioning effectiveness is modeled as a customer-based multidimensional construct capturing conceptually relevant dimensions of positioning success (namely dissimilarity, uniqueness, favorability, and credibility) at the holistic product level rather than the individual attribute level. Altogether seven studies show that the proposed positioning effectiveness measure is reliable, valid, and viable to be used across various types of branded products and distinct product categories. The results of the studies indicate the measure's ability to successfully predict important consumer behavior variables such as overall superiority or purchase intentions and demonstrate superior predictive performance compared with common attribute-based approaches. The recognition of the relevance of different dimensions of positioning effectiveness should also enable new product managers to detect strengths and weaknesses of a product's current positioning, and thus serve as a tool to develop more effective product strategies. The general nature of the measurement instrument makes it particularly suitable for application in (1) longitudinal product-tracking studies; (2) cross-national studies involving comparisons of positioning effectiveness between products in different countries; (3) product categories characterized by technological turbulence (and hence attribute instability); and (4) studies aimed at comparing the positioning effectiveness of different products in a portfolio. Boundary conditions for the application of the measure and potential areas for further study are finally considered.