At the heart of 23,000-acre Rancho Mission Viejo, a master planned community (MPC) in Orange County, Calif., is a 172-year-old working cattle ranch—the only remaining one in a county that once teemed with them. The development’s growing neighborhoods, which eventually will sprout 14,000 homes, are rising around a 17,000-acre permanently protected habitat reserve, where cowhands raise the cattle. Inside the community’s gates, homeowners can work alongside farmers tending Orange County’s largest citrus orchard, chicken coops, and three working farms that produce row crops and herbs.