The purpose of this study was to examine the effect of two different reciprocal peer-assisted learning (PAL) arrangements on music achievement and learner engagement in the secondary instrumental music classroom. Using a quasi-experimental design, students from six separate seventh-grade bands from one large urban/suburban school district (N = 261) were randomly assigned to one of two treatment conditions: symmetrical PAL, where students of like ability were paired together, and asymmetrical PAL, where students of divergent ability were paired together. Students worked in pairs over the course of four weeks and took turns being the "learner" and the "teacher" to improve sight-reading ability and music theory knowledge. Student pairs were allowed to determine their own rules for interaction, turn taking, and the amount of material to be covered in each session. Three pre-/posttest outcome variables were assessed: sight-reading performance, music theory knowledge, and learner engagement. Additionally, individual socioeconomic status (SES) and motivation orientation were compared as potential moderating variables. Hierarchical linear regression analyses indicated that regardless of PAL pairings, there were significant gains for each of the outcome variables. Moreover, interaction effects were found between learner engagement, method of instruction, and SES.