This article presents the process of translation into Spanish, adaptation, and validation of the General Musical Self-Efficacy Scale by Ritchie and Williamon. After having carried out reverse translation and a preliminary study, the scale was tested on a sample of 668 students enrolled in six Spanish music academies (secondary school and university level). Our results corroborated the two original subscales: one for self-efficacy for learning (α = .792 and α = .734), and the other for self-efficacy for public performance (α = .773 and α = .780), after having removed one item in each subscale on the basis of internal consistency indicators and factorial analysis. The subscales we thereby obtained likewise presented good temporal stability ( r = .513 and .539); they both correlated with performance anxiety (stage fright); both correlated more highly with the public performance subscale. Validation data signaled higher scores obtained by students enrolled in university-level music academies, by students who had started music training at an earlier age, for the boys at secondary level, and for the younger group of students at secondary level. To summarize, this version of the General Musical Self-Efficacy Scale is a valid, reliable tool for measuring self-efficacy in Spanish music students.