Prior research emphasizes the paradoxical nature of coopetition and the need for specialized capabilities—coopetition capability—to deal effectively with opportunities and challenges stemming from the simultaneous pursuit of cooperation and competition and to create superior value. However, we know little about the underlying conceptual properties of coopetition capability (construct clarity) and lack a reliable and valid scale to measure it (construct validity). We conduct a study in three phases to address this critical gap. First, building on paradox literature, we conceptualize coopetition capability as a multidimensional construct reflected by three underlying dimensions: coopetition mindset, analytical acumen, and executional skills. Second, we develop a 15-item psychometrically valid scale using a sample of 647 coopetitive alliances in high-technology sectors. Finally, using a matched sample of 536 coopetitive alliances, we extend the focal construct's nomological network by examining two relationships: coopetition experience's impact on coopetition capability and the effect of coopetition capability on the relationship between the coopetition paradox and value creation. Overall, our paper lays a foundation for deeper theory development and empirical research on coopetition by providing much-needed construct clarity and psychometrically valid measures for coopetition capability.