By showing how the addition of three universities to the State University System of Florida affected enrollment projections for the six older universities, a tool was developed that may be of use for enrollment projections in other settings, when the system changes. County population and K-12 school enrollment project reasonably well the undergraduate enrollment of students from those counties not strongly influenced by the new universities, at those universities that are not expanding by virtue of new program addition themselves. Treatment of enrollment from counties influenced by the opening of new universities includes the assumption of "constant relative probability." The projection incorporates the probabilities for attending the new university and for attending the given university before the new one opened. Under sufficiently controlled conditions, the projections give reasonable agreement with observed enrollment changes. (Author/JMD)