We use the position fixes and temperature readings from 56 Tristar-II mixed-layer drifters, in conjunction with advanced very high resolution radiometer images, to provide a description of the mesoscale variability of the flows associated with cold-water filaments in the California Current system off northern California in July 1988. We find that the northern, offshore temperature front of the filament is convergent and is closely associated with the core of a high-speed (>100 cm/s) jet that has a broader spatial scale than the cold-water filament. Mesoscale features are observed to be related to all developments of the cold-water filament on a variety of time scales (1--30 days). In one well-observed feature, estimates of vertical velocity (w) based on a vorticity budget are -20 m/d over an area of 150 km2 and are associated with a gain of vorticity. Estimates of w based on a local heat budget following a drifter are about 3 times larger over an area of 60 km2. These intense downwelling features are also places where horizontal stirring occurs. ¿ American Geophysical Union 1992