When first adopted by California local governments in the 1980s, right to-farm ordinances were seen by many farm leaders, real estate people, and public officials as an easy response to the problem of urban growth encroaching on adjacent farm operations. Such measures have little regulatory effect, but seek to reduce the opposition of urban neighbors to commercial agriculture as a nuisance generator. Most ordinances require that homebuyers who move to parcels adjacent to or near working farms and ranches be notified about the possible negative impacts of agricultural activities. In this way, the theory goes, new residents–especially those unfamiliar with rural living–would effectively learn about the realities of modern farming and would be less inclined to complain, or even go to court, about sprays, dust, odors, noise and other aspects of agricultural activities. The normal practices of farmers and ranchers would thus be protected. The local ordinances are now widespread throughout California’s agricultural regions. About 40 counties and 50 cities currently have these measures. Despite their popularity, questions are frequently raised about the effectiveness of right-to-farm ordinances in protecting agricultural operations and reducing farm- urban edge conflicts. The two principal reasons are: (1) considerable variation in implementation from one jurisdiction to another, and (2) the generally benign and undemanding character of disclosure requirements, as compared to the more stringent regulatory tools of zoning, buffers, and subdivision review. This assessment is based on a comparative study of county-adopted ordinances and their implementation in 15 agricultural counties 2 located in Central Valley and coastal regions 3 . (This study does not cover city ordinances which apply just to areas within incorporated boundaries.) We examined each of the county ordinances and conducted phone interviews with about 40 knowledgeable local persons, including agricultural commissioners, county planners, agricultural (Farm Bureau) leaders, real estate representatives, and UC Cooperative Extension staff.