Quenching and partitioning (Q&P) is receiving increased attention as a potential processing route to develop “Third Generation” advanced high strength steel (AHSS) properties. The Q&P process consists of quenching a steel from a reheat temperature to a pre-determined temperature in the Ms − Mf temperature region followed by a so-called partitioning treatment at the quench temperature or higher. The present contribution investigates the Q&P response of laboratory-processed CMnSi alloys with 3 or 5 wt% manganese. Samples were processed at quench temperatures between 70 and 250°C with partitioning temperatures of 400 and 450°C for times up to 100 s. Scanning electron microscopy and X-ray diffraction were utilized to evaluate the Q&P microstructures. Attractive properties were generated with tensile strength/total elongation combinations such as 1500 MPa and 17%.