The stability of an M.I.T. typo model-reference adaptive control system when subjected to random inputs and disturbances is considered. Conditions for both stability in the mean square and almost sure asymptotic stability are obtained using the theory of Markov processes, involving use of the Fokker—Planck equation, and the second method of Liapunov. Limitations and difficulty of application of the theory are discussed and the theoretical stability boundaries obtained comparod to those obtained by digital simulation of the system.