Los Angeles County, the most populous county in the United States, is home to 10 million people and 88 municipalities. It is larger than 41 of the 50 states. Comprising urban centers, extensive suburbs, and low-income, rural, and agricultural communities, it poses complex public health challenges that are diverse in scope and unmatched in scale.

In Public Health Practice: What Works, the leaders of LA County's Department of Public Health compile the lessons and best practices of working in a complex and evolving public health setting. Through stories of success (and challenges)...