Novel sensor have been developed at the Army Research Laboratory (ARL) to provide continuous accurate angular measurements for spinning projectiles in free flight. These systems, which directly measure angular orientations, are distinct from angular rate sensor methodologies that require integration of these rates to estimate angular orientations. Also, many traditional rate sensors are expensive, voluminous and not well-suited to the high-g launch and high spin environment of many projectile-borne munitions. Recent advances in commercially-available magnetic sensors have yielded devices small enough, rugged enough, and/or sensitive enough to be used in body-fixed sensor constellations to make high-speed, high-resolution measurements of attitude and roll rate relative to earth's magnetic field. The addition of a complimentary sensor system measuring orientation relative to another distinct earth-fixed field of known orientation provides the information required to mathematically determine the absolute angular orientation of a spinning body within any desired navigation system, e.g., north, east, and vertical. Such a dual-field measurement system has been implemented utilizing a unique constellation of magnetoresistive sensors and ARL Solar Likeness Indicating Transducers (SLIT) to determine angular orientation with respect to the magnetic and solar fields respectively. The mathematical foundations of this dual-field sensor system will be summarized and flight experiments of the prototype systems will be discussed.