Abstract : Three investigations have been completed under the contract entitled 'Laser Gyro Theory Extension,' as follows: (1) The accuracy of the Zeeman laser gyro (ZLAG) theory was tested by comparing its predictions with experimental results. (2) Other multioscillator approaches to solving the lock-in problem have been investigated. (3) Two earthbound experiments to test general and special relativity theories were designed, based on the Sagnac interferometer. (Author)