Unlike dense media separation, froth flotation has no widely accepted counterpart to float-sink analysis for characterizing process performance. However, release analysis, developed by C.C. Dell in 1953, could serve as this counterpart by providing a measure of the "state of release" or ultimate separability of a sample by froth flotation. In an attempt to encourage the acceptance of this technique as a standard for characterizing flotation performance, release analysis has been carried out on a variety of U.S. coals including Pittsburgh No. 8, Upper Freeport and Illinois No. 6. Tests conducted as a function of various frother types and frother and collector dosages indicate that the release curve is relatively independent of these parameters. Run-of-mine coals, generally containing large amounts of free mineral matter, produce superior release curves to precleaned samples of the same material, while increased grinding lends to improve the release curve. When compared to centrifugal float-sink analysis, release analysis produces an inferior separation, indicating that float-sink data are not appropriate for characterizing a surface-based process such as froth flotation.