We investigate the extent to which the paleotracers, Δ13C and Δ18O, constrain the North Atlantic Ocean general circulation during the last glacial maximum (LGM). The distinction is made in this work between the depiction of water mass distributions and the inference of the oceanic circulation. The Δ13C data indicate that water masses formed in the North Atlantic and in the Southern Ocean were distributed differently during the LGM, but the extent of the differences cannot be quantified because of uncertainties in the end-member composition. Reasonable choices of values for the end-members produce volumes of Lower North Atlantic Deep Water (NADW) significantly smaller than in the modern Atlantic, in agreement with previous studies. To explore the range of circulations consistent with this water mass distribution, a coarse resolution inverse model of the North Atlantic is constrained with Δ13C and Δ18O paleodata. The model shows that the glacial period tracer distribution is fully consistent with the circulation rates estimated for the modern ocean. However, the paleodata are also consistent with a circulation rate of one-half the modern flux of NADW, and indeed there are an infinite number of rates of deep water movement that are possible. To remove this ambiguity, the central need is for a data type capable of setting the overall rates of water movement, i.e., a ''clock,'' such as that provided by geostrophy or a well-sampled radioactive tracer. ¿ American Geophysical Union 1995<