Radar polarimetry with multi-parameter measurements has matured to the point that it has been implemented on the national network of WSR-88D Doppler radars. While the technology of radar polarimetry has matured, and polarimetric radar data (PRD) are available nationally and worldwide, radar polarimetry is still in its initial stages for operational usage. There is a lot of room for research and development, especially in using PRD. Phased array technology has recently been introduced to the weather community to increase data update rates to lengthen the lead-time of weather hazard warnings. Polarimetric phased array radar is desirable for future weather observations and multi-mission capabilities. This short course will provide the background information on weather radar polarimetry and polarimetric phased array radar (PPAR) and its applications, and will introduce the latest advances in research and development of a PPAR that can serve the multiple functions (e.g., weather and aircraft surveillance).