Santa Rosa is the county seat of Sonoma County, California, USA. As of January 1, 2007, the population of Santa Rosa was approximately 157,985 residents. Santa Rosa is the largest city in California's Wine Country and fifth largest city in the San Francisco Bay Area, after San Jose, San Francisco, Oakland, and Fremont. Santa Rosa apartments for rent comparison page shows most up to date rent information on Santa Rosa apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.