Preface. Introduction. The oceanographic data assimilation problem: overview, motivation and purposes (P. Malanotte-Rizzoli, E. Tziperman). Models and Data. Recent developments in prognostic ocean modeling (W.R. Holland, A. Capotondi). Oceanographic data for parameter estimation (N.G. Hogg). A case study of the effect of errors in satellite altimetry on data assimilation (L.L. Fu, I. Fukumori). Ocean acoustic tomography: integral data and ocean models (B.D. Cornuelle, P.F. Worcester). Global Applications. Combining data and the global Primitive Equation Ocean General Circulation model using the adjoint method (Z. Sirkes, E. Tziperman, W.C. Thacker). Data assimilation methods for ocean tides (G. Egbert, A.F. Bennett). Global ocean data assimilation system (A. Rosati, R. Gudgel, R. Miyakoda). Tropical Ocean Applications. Tropical data assimilation: theoretical aspects (R.N. Miller, M.A. Cane). Data assimilation in support of tropical ocean circulation studies (A.J. Busalacchi). Data assimilation as a component of a coupled forecast system (A. Leetmaa, M. Ji). Regional Applications. A methodology for the construction of a hierarchy of Kalman filter/smoothers for nonlinear primitive equation models (P. Malanotte-Rizzoli, I. Fukumori, R.E. Young). Data assimilation in a North Pacific Ocean monitoring and prediction system (M.R. Carnes et al.). Toward an operational nowcast/forecast system for the U.S. East Coast (F. Aikman et al.). Real-time regional forecasting (A.R. Robinson et al.). Interdisciplinary Applications. An interdisciplinary ocean prediction system: assimilation strategies and structured data models (C.J. Lozano et al.).