It has been known for some time that a frontal zone exists in the slope water, which lies between the Gulf Stream and the shelf break off Nova Scotia, where the temperature jumps from 7 ¿C to 11 ¿C and the salinity from 34.8% to 35.2% in a horizontal distance of a few kilometers. Data taken from this area with a yo-young CTD (conductivity-temperature-depth probe) have been analyzed and show that at the front the two water masses interleave with a vertical scale of the order of 10 m. The interleaving layers are coherent for several kilometers in the cross-frontal direction and for at least 17 km in the long-frontal direction. The data suggest that considerable vertical mixing, through double diffusive processes, and horizontal mixing, through interleaving processes, occur in the frontal zone. Vertical eddy coefficients of 8¿10-4 m-2/s for heat and 3¿10-4 m2/s for salt are calculated for the water column between 40 and 160 m at the front by using Turner's (1965, 1967) formulae to calculate the double diffusive fluxes across the m at the front by using Turner's (1965, 1967) formulae to calculate the double diffusive fluxes across the interfaces of the layers. The horizontal eddy diffusion coefficients at the front are calculated to be 10 m2/s for heat and 9 m2/s for salt. The estimated annual vertical heat flux at the front into the coastal water is 15% of the solar input to the shelf water, and the salt flux is 10% of that needed to produce shelf water from the freshwater runoff. Horizontal mixing across the front is shown to be large enough to explain the observed annihilation of the Labrador Slope Water during the time it takes to travel along the Scotian Shelf. The high vertical mixing at the front may provide a significant vertical nutrient flux.