The emergency medical services (EMS) system is a component of a larger health care safety net and a key component of an integrated emergency health care system. EMS systems, and their patients, are significantly impacted by emergency department (ED) crowding. While protocols designed to limit ambulance diversion may be effective at limiting time on divert status, without correcting overall hospital throughput these protocols may have a negative effect on ED crowding and the EMS system. Ambulance offload delay, the time it takes to transfer a patient to an ED stretcher and for the ED staff to assume the responsibility of the care of the patient, may have more impact on ambulance turnaround time than ambulance diversion. EMS administrators and medical directors should work with hospital administrators, ED staff, and ED administrators to improve the overall efficiency of the system, focusing on the time it takes to get ambulances back into service, and therefore must monitor and address both ambulance diversions and ambulance offload delay. This paper is the resource document for the National Association of EMS Physicians position statement on ambulance diversion and ED offload time. Key words: ambulance; EMS; diversion; bypass; offload; delay.