Jean-Paul MICHAUD gives an account of the profusion of contemporary studies on Q, the hypothetical documentary source of Jesus' words. The first part focuses on Q's existence. Since this issue is intrinsically connected with the synoptic problem, the range of solutions proposed for the latter is reviewed and, finally, the contention is made that the so-called Two-Source Theory (Mark and Q) is the ... [Show full abstract] most plausible of those solutions. The second part considers the hypothetical document itself: its nature, reconstruction, compositional history, content and milieu of redaction. Although it is not always acknowledged, Q research is related to the search for the Jesus of History and is very often motivated by it.