This chapter provides an overview of the role of algorithmic recommendation in contemporary music streaming services, describing how they work, how they relate to other algorithmic applications, and problems that have emerged from their use. Against a dominant discourse that pits algorithms against humans, it argues that contemporary recommender systems are best understood as ‘ensembles’, comprising a variety of algorithmic and human parts working in conjunction with each other. This suggests new directions for research, focusing not on the intrinsic character of human or algorithmic mediation, but rather how this sociotechnical ensemble is composed and conducted. The issues raised by algorithmic music recommendation are not new but variations on past concerns including payola, the treatment of so-called world music and the power of cultural intermediaries.