Abstract: The California Invasive Plant Inventory categorizes non-native invasive plants that threaten the state’s wildlands. Categorization is based on an assessment of the ecological impacts of each plant. The Inventory represents the best available knowledge of invasive plant experts in the state. However, it has no regulatory authority, and should be used with full understanding of the limitations described below. California is home to 4,200 native plant species, and is recognized internationally as a “biodiversity hotspot.” Approximately 1,800 non-native plants also grow in the wild in the state. A small number of these, approximately 200, are the ones that this Inventory considers invasive. Improved understanding of their impacts will help those working to protect California’s treasured biodiversity.