An examination of the costs of congestion delay at La Guardia Airport, New York, and possible changes in fees to reduce them. At present, each additional airliner arriving or departing between 3:00 and 4:00 p.m. imposes an average of $1,000 in delay costs on other users, and one more non-airline plane costs others more than $500. Full marginal cost pricing, imposing congestion tolls, is probably infeasible, in part because airline lessees must agree to any change to the present weight-based fees. Therefore, a proportional marginal cost pricing system is proposed that would not raise total airline costs but would tend to discourage low-value general aviation at peak hours. Administrative measures to encourage efficiency would still be needed. 28 pp. Ref.