Thirty-five expendable bathythermograph sections and 10 Pegasus velocity sections taken approximately normal to the Gulf Stream northeast of cape Hatteras were used to examine the variability of the current's structure. The regridded profiles were superimposed in a stream coordinate system such that the temperature variance associated with the superposition was minimized. The resulting variance field was examined using empirical orthogonal functions. The temperature variability is heavily weighted by seasonal warming; hence the following results exclude temperatures from the upper 200 m. The first mode (48% of the variance) is due to a deepening of the inshore edge, associated with a change of geostrophic velocity and baroclinic transport. The amplitudes of this ''transport mode'' indicate a slight downstream increase in baroclinic transport (~2% per 100 km) and a seasonal modulation (5 Sverdrups rms) that peaks in May--June. The second temperature mode below 200 m (13--21% of the variance) is associated with a change in horizontal shear, a ''vorticity mode,'' and is positively correlated with measured path curvature and layer thickness. The directly observed Pegasus velocity sections were combined with corresponding temperature sections to compute their joint empirical modes. The dominant combined mode has a thermocline structure change as in the transport mode that is coupled with an increase in alongstream velocity and, for levels above the main thermocline, an inflow from both sides toward the center. Both temperature and velocity data indicate that high transport in the Gulf Stream is associated with lateral displacement offshore of its mean position. ¿ American Geophysical Union 1989