IAAO is a nonprofit, educational, and research association. It is a professional membership organization of government assessment officials and others interested in the administration of the property tax. IAAO was founded in 1934, and now has a membership of more than 7,000 members worldwide from governmental, business, and academic communities.

Los Angeles County Chapter consists of officers of the largest local public property assessment agency in the nation. Los Angeles County Assessor Jefferey Prang and staff of nearly 1,400 appraisers and support staff are dedicated to creating an accurate and timely property assessment roll. Last year, the Los Angeles County Assessor's Office established values for 2.6 million properties valued at more than $1.2 trillion.