This report presents the results of our self-initiated audit of Efficiency of Operations at the Margaret L. Sellers (MLS) Processing and Distribution Center (P&DC) in San Diego, CA (Project Number 22-061). We conducted this audit to provide U.S. Postal Service management with timely information on operational risks at this P&DC. We judgmentally selected the MLS P&DC based on overtime, penalty overtime, late and extra trips, and low clearance time percentage for package processing. The MLS P&DC is in the Southern California Division; processes letters, flats, and parcels; and services multiple 3-digit ZIP Codes in urban and rural communities (see Table 1).