Chemically enhanced primary treatment can provide enhanced total suspended solids removal. With these enhanced removals, enhanced removals of other pollutants are realized as well. Jar tests that are typically performed to evaluate chemically enhanced primary treatment provide information only on the extent of the flocculation reaction, not the rate of the flocculation reaction. A procedure is presented that measures both the extent and the rate of the flocculation reaction using a modified jar testing procedure. The procedure was used in a full-scale evaluation of chemically enhanced primary treatment.