Modeling represents the synthesis of our process understanding as well as an approach for testing our current understanding of various biogeochemical cycles. With sufficient development, models can be used to examine sampling strategies for process studies as well as large scale observations. In the near term, models also suggest possible linkages where improved understanding will provide the greatest advantage. U.S. JGOFS views models in all these ways, however, our objective is to provide a useful synthesis of our understanding which can be used for diagnosis of the current ocean role in the carbon system, as well as for future forecasts of the ocean state. Modeling efforts supported directly through the U.S. JGOFS program have been rather limited. Some modest model studies were made in advance of all the major process studies to help define issues and priorities for the field programs. Until FY 1996, only about 3% of U.S. JGOFS funds were used for model studies. Now that the field programs are winding down, this situation has begun to change dramatically. A major new initiative, the U.S. JGOFS Synthesis and Modeling (SMP) project has been started Its central objective is to synthesize knowledge gained from U.S. JGOFS and related studies into a set of models that reflect our current understanding of the ocean carbon cycle and its associated uncertainties. Emphasis will be given to processes that control partitioning of carbon among oceanic reservoirs and the implications of this partitioning for exchange between the ocean and atmosphere. The first of several Announcement of Opportunities for support of SMP projects was issued by NSF in early 1997 and the level of support is expected to ramp up into a major ongoing effort to crystallize the advances in understanding of the ocean carbon cycle through US JGOFS. In anticipation of this, support of synthesis activities began through the US JGOFS Planning Office during the last grant cycle. Support was provided for major data and synthesis workshops for the Equatorial Pacific and Arabian Sea Process Studies - and will be continued for the Southern Ocean Study. Production and dissemination of Special Issues of Deep-Sea Research was supported for Time-Series and Equatorial Pacific research and synthesis papers. The first annual major SMP workshop was held in August 1996 in New Hampshire and a second one is planned for August 1997 (emphasizing Time-Series Synthesis). A Synthesis and Modeling Steering Committee, headed by Jorge Sarmiento and Scott Doney, was set up by the US JGOFS Steering Committee to provide the necessary oversight and guidance to the SMP program. They will act in a manner analogous to the Process Studies coordinators who provided the leadership for each study.