In the study of human motivations, self-interest is often seen as a determining factor and opposed to other-interest. Recently a new conceptualization has been proposed in which both interests can occur at the same time. In order to measure these constructs, the Self-and Other-Interest Inventory (SOII; Gerbasi & Prentice, 2013) was created, which has one version for adults and one for students. Due to the absence of similar measurement instruments in Spain, the aim of this work is to adapt the SOII to Spanish university students. Several studies were conducted. First, the construct was analyzed through rational-analytical procedures. Second, the items were translated following an iterative forward-translation design. Finally, evidence of validity was obtained through analytical procedures. Specifically, two pilot studies were carried out in which two independent samples of Spanish students participated (N1 = 119; N2 = 165). In both studies descriptive analyzes of the items were performed, reliability was estimated and the factor structure of the SOII was explored from an exploratory factor analysis. The results showed adequate reliability and a two-factor solution consistent with the original.