Kraljic's purchasing portfolio approach has inspired many academics to undertake further research into purchasing portfolio models. Refined models typically recommend one purchasing strategy for each portfolio quadrant. Yet, it has been shown that purchasers make a clear distinction between alternative purchasing strategies within each quadrant. The fundamental assumption of portfolio models seems to be that differences in power and dependence between buyers and suppliers exist. Still, little is known about how these concepts influence the choice for a specific purchasing strategy. In this paper, ‘relative power’ and ‘total interdependence’ for a number of portfolio-based purchasing strategies have been quantified empirically, using data from a comprehensive survey among Dutch purchasing professionals. The survey data largely confirmed the hypotheses that were deduced from the literature.