This book brings together the thinking of twenty-two eminent astronomers on a fascinating topic of contemporary astrophysics: large-scale galaxy motions. Stars group into galaxies, galaxies unite into clusters, clusters merge into superclusters, and superclusters meet at intersections of filaments to define voids and supercluster complexes. Can gravity alone, arising from this irregular mass distribution, produce the motions which observers detect? In this collection, astronomers discuss evidence for irregular clumping of galaxies throughout the observed universe, determination of galaxy peculiar motions, and predictions from theories of the early universe relating to small-scale fluctuations in the microwave background radiation, the lumpy matter distribution, and large motions. This book can serve as a companion volume to The Large-Scale Structure of the Universe by P.J.E. Peebles (Princeton, 1980). Authors of chapters in the book include N. A. Bahcall, J. R. Bond, D. Burstein, M. Davis, A. Dekel, G. Efstathiou, S. M. Faber, M. Geller, M. P. Haynes, J. P. Huchra, N. Kaiser, D. C. Koo, A. N. Lasenby, D. Lynden-Bell, J. Mould, P.J.E. Peebles, V. C. Rubin, A. Szalay, R. B. Tully, N. Vittorio, and A. Yahil.