The Oil and Hazardous Materials, Technical Assistance Data System (OHM-TADS) is an automated information retrieval file specifically designed to facilitate rapid access to data on 1,402 oil and hazardous substances. OHM-TADS provides vital information to spill response team personnel, especially in emergency situations where readily accessible information on the degree of the hazards involved, appropriate countermeasures, and effective personnel safety precautions is of critical importance. Quantitative data and interpretative comments found in the 126 fields that constitute OHM-TADS can be used as a basis for decision making and initiation of corrective action for both on-scene coordinators and emergency response teams. Additionally, OHM-TADS covers regulatory information, including shipping requirements and water standards, as well as a wide variety of physical, chemical, biological, toxicological, and commercial data of value for enforcement and research activities. Sources of information presented in OHM-TADS include journal articles, symposia papers, government reports, and basic reference texts.