The binding problem is frequently discussed in consciousness research. However, it is by no means clear what the problem is supposed to be and how exactly it relates to consciousness. In the present paper the nature of the binding problem is clarified by distinguishing between different formulations of the problem. Some of them make no mention of consciousness, whereas others are directly related to aspects of phenomenal experience. Certain formulations of the binding problem are closely connected to the classical philosophical problem of the unity of consciousness and the currently fashionable search for the neural correlates of consciousness. Nonetheless, only a part of the current empirical research on binding is directly relevant to the study of consciousness. The main message of the present paper is that the science of consciousness needs to establish a clear theoretical view of the relation between binding and consciousness and to encourage further empirical work that builds on such a theoretical foundation.