Mission Viejo is a city in Orange County, California, United States in the Saddleback Valley. Mission Viejo is considered one of the largest master-planned communities ever built under a single project in the United States, and is rivaled only by Highlands Ranch, Colorado, in its size. 

Mission Viejo is suburban in nature and culture. The city is mainly residential, although there are a number of offices and businesses within its city limits. The city is known for its tree-lined neighborhoods, receiving recognition from the National Arbor Day Foundation. The city’s name is a reference to Rancho Mission Viejo, a large Spanish land grant from which the community was founded.

Mission Viejo is steeped in a tradition that dates back to the vanishing days of men on horses driving cattle.  Nearly 25 years ago, the Mission Viejo Co. bought a 10,000-acre section of Rancho Mission Viejo from the O’Neill family, which once owned much of the land from Oceanside to El Toro.  The company would create a master plan for a community, specifying the number of parks, homes, recreational activities and retail spaces.  The rolling hills of the valley, home to a sea of grazing cattle, soon would also become home to seekers of “The California Promise.”

The vision for the community began in 1963 with a planners blueprint. The general development plan wound its way through the maze of county permits and by 1966 the first homes were sold, according to the Mission Viejo Co.  Fewer than a handful of changes – among them the additions of Saddleback College and lake Mission Viejo – have been made to that initial plan.  Currently, over 100,000 people call Mission Viejo home.