Abstract: After World War II, hillside development has increasingly served as a critical approach to mitigate urban land shortages. The analysis of relevant regulatory documents proves efficient for identifying hillside regulation purposes and strategies of different cities. Focusing on cities in the United States, existing summary studies have failed to reveal the relationship between governments at various levels as well as the changing trends of their regulatory strategies. This paper presents a case study of metropolitan Los Angeles by systematically examining 44 hillside plans, ordinances, guidelines and studies collected from relevant city, county, state, and federal governments. The results show that the government agencies often give priority to three regulatory purposes, including ecological protection, public safety, and outdoor recreation. While their jurisdictional areas’ elevations generally have positive correlations with their administrative levels, most of these agencies have been intervening in the hillsides adjacent to urban centers. Chronologically, the four-level governments have taken three types of regulatory strategies, including protected areas, overlay zones, and co-governance, which tend to be flexible and inclusive. For China, the Los Angeles experience has two implications: one is to make creative adjustment to the existing system of land use zoning, and the other is to establish cooperative partnership between government departments at all levels and local communities.