Recently, Monopoli lias developed a scheme for designing a stable model reference adaptive control system without requiring plant output derivatives, introducing the concept of an augmented error signal. In this paper we propose modifying his scheme by using a lower order reference model, reducing the augmented error equation into a first-order form and adding a proportional term to the integral adaptive law. These modifications offer the following advantages : (1) implementation of the overall adaptive control system can be simplified ; (2) the required adaptive law can be simply derived without using the Meyer-Kalman-Yacubovich lemma ; and (3) response characteristics of the adaptive system can be greatly improved. Computer simulation results are included to demonstrate the effectiveness of our scheme.