The oscine passerines, or 'songbirds', are one of the few animal taxa in which individuals learn their vocal signals. Recent comparative studies reveal a remarkable diversity of song-learning strategies in the songbirds. Here, we discuss recent studies that shed light on the possible functional basis of different song-learning programs. We argue that further insights into the evolution and ecology of song learning will require that comparative data and functional hypotheses be analyzed in a phylogenetic context, and we review recent studies that we feel might be the first steps in this process.