This investigation was concerned with determining the optimum team mix for a dental practice utilizing expanded duty dental assistants (EDDAs). A live, surrogate practice provided the basis for a computer-simulated private practice in which one dentist worked with various combinations of chairside assistants and expanded duty auxiliaries. This "composite dentist" was of average speed as an operator, functioning under conditions of an external quality control mechanism. Results indicated that the optimum team size, from the standpoint of both productivity and economic considerations, involved one dentist, one EDDA, and two assistants, as compared with the control team of one dentist and two assistants. Experimental teams involving two EDDA's, studied both with and without chairside assistants, were counterproductive from a financial standpoint. Various factors influencing team size are discussed, but dentist operator speed emerges as a major determinant of optimum team mix.