This investigation explored collaborative problem solving with and without a coach by analyzing problem-solving (PS) and problem-solving-prompting (PSP) behaviors by group members and coaches in six total coached rehearsals with three collegiate string quartets, and six autonomous rehearsals with the same string quartets. Teachers' and learners' PS and PSP behaviors were compared in three settings: autonomous chamber music rehearsals, chamber music rehearsals with a coach, and one-to-one instruction. Coaches and students performed the same problem-solving component behaviors and most of the same PSP behaviors as observed in one-to-one instruction and in rehearsals of a professional chamber ensemble. As in one-to-one instruction, coaches could engage learners in problem solving, and in this setting invite them to collaborate with one another, by asking questions and varying the specificity of feedback and directives. Coaches' Attention Directives preceded the most learner problem solving and collaborative engagement. During autonomous rehearsals learners often switched leadership roles fluidly, often prompting one another to problem solve. Implications for a pedagogy of coaching and inclusion of small ensembles within music education are discussed.