The ESEA Title I evaluation Technical Assistance Centers (TACs) assist state and local education agencies to implement the Title I Evaluation and Reporting System (TIERS), to improve the quality of evaluation information, and to use evaluation results for local decision making. This paper reports on the results of one method of assessing the impact of TACs in these three areas by comparing contact logs for 1977-78 and 1980-81 for types of topics covered, the level of difficulty of the material covered, and the mode of service delivery. Preliminary results show that there have been major changes in three areas: increasing variety of evaluation topics in which clients are interested, increasing emphasis on topics dealing with local use of evaluation results, and an increasing number of topics covered at a "refinement" level of sophistication. These changes seem to be the result of several forces interacting with each other--evolution in the TACs, evolution of the Federal policy, and evolution in the state and local education agencies. Measures of TAC impact have implications for design of future technical assistance efforts. (Author/BW)