Transmission electron microscopy (TEM) was used to examine the morphology of blends of nylon 6 and polypropylene (PP) containing various maleated polypropylenes (PP-g-MA). The size of the dispersed polypropylene particles decreases as the content of maleic anhydride in the PP-g-MA increases for binary blends of nylon 6 and the maleated polypropylenes. Ternary blends of nylon 6, PP, and PP-g-MA show morphologies that depend on the content of maleic anhydride of the PP-g-MA and on the miscibility of PP and PP-g-MA. Blends where PP and PP-g-MA are immiscible show a bimodal distribution of particle sizes. Miscibility of the PP and PP-g-MA was determined by TEM using a special staining technique. Experimental observations of miscibility were further corroborated by thermodynamic calculations. The morphology of the ternary blends was also found to be dependent on the ratio of PP/PP-g-MA. By changing this ratio it was possible to induce drastic changes of morphology, going from a continuous nylon 6 phase to a continuous PP phase at a fixed composition. The mechanical properties of these blends were found to be dependent on their morphology.