As an independent system operator, the Electric Reliability Council of Texas (ERCOT) is responsible for the security and reliability of the ERCOT grid. Participation by load in the restructured ERCOT market is viewed as a means of enhancing competition in those markets, mitigating unwarranted price spikes, and preserving system reliability. Customers with interruptible loads that can meet various performance requirements can be qualified to provide operating reserves under the load acting as a resource (LaaR) program. Qualified LaaRs can participate into various ancillary services to maintain and enhance the system reliability. This paper introduces the successful LaaR program in the ERCOT market, and operation experiences to maintain and enhance the system security through load participation in the LaaR program.