Follow Through Evaluation in Philadelphia has adopted a comprehensive documenting approach, the core of which is an individual pupil file containing coded information indicating length of program exposure (in terms of five or more months per year) for each year of pupil enrollment. A study of the relationships between pupil achievement on the Stanford Early School Achievement Test, Metropolitan Achievement Tests, and Iowa Tests of Basic Skills and pupil length of program exposure seems to indicate growth in achievement as a function of exposure, particularly in two of the seven models used in Philadelphia. (Author)