Educational Service Unit (ESU) 18 is an independently funded agency providing evaluation services for the Lincoln (Nebraska) Public Schools. ESU employees provide direct services on a regular basis to the school district. A close working relationship exists between members of the ESU and district staffs. Consequently, as the occasion requires, the ESU evaluator can provide the responsiveness characteristic of internal evaluation while maintaining the credibility of an external evaluator. After a brief discussion of the organization of ESU 18, this paper describes the Evaluation Team's role in a multi-year study of a school district's reading program. Throughout the development and implementation of the revised reading program ESU evaluators have supported district efforts by conducting a series of evaluation studies. This multi-year cooperative effort is a good example of the responsiveness, timeliness, and accessibility fostered by the ESU structure for providing services to the schools. (Author/GK)