The California HIgh school Cosmic ray ObServatory (CHICOS) is a collaborative project involving Caltech, Cal State Northridge, UC Irvine, and local high schools to site a large array of particle detectors in Southern California. The detectors are located on school rooftops, and utilize the power and network infrastructure available at the schools. The main scientific goal is to study cosmic rays at ultra-high energies E>1019 eV. We have fielded a total of 23 sites so far, and are beginning to collect data as we continue to deploy additional sites. We have observed our first evidence of extended air showers in coincidence with a local high school. The anticipated performance of the initial array and the potential for future expansion will be discussed.