An urban district hired consulting teachers to assist in the implementation of instructional improvement programs in elementary schools with high proportions of low income, minority students. Two distinct academic programs using mastery learning techniques were offered--one fairly structured and the other highly structured. The consultants oversaw student placement, ensured the presence of suitable materials, monitored teacher implementation of the programs, and provided technical assistance. A study analyzing the role of these consultants involved extensive observations of the consultants' day-to-day operations in four large schools, interviews with the 105 teachers and 24 aides served by the consultants, interviews with and observations of the school principals, observations of teachers using the new methods, and observation of staff meetings concerning instructional issues. The study found that the improvement efforts had significantly changed the nature of teaching and the success of students in the schools. The consultants apparently played an important role in these changes, particularly through their visible commitment and their clear presentation of many concepts. Their impact was limited, however, due to official restrictions related to teacher autonomy and due also to insufficient preparation in the concepts of teacher effectiveness. (PGD)