Recent increased regulatory restrictions on the use of a first-generation anticoagulant rodenticide, diphacinone, were put into place in California in January 2024 by the passage of California Assembly Bill 1322 in late 2023. Second-generation anticoagulant rodenticides were listed as California Restricted Materials in 2014, and their uses were further restricted in 2021 with the passage of California Assembly Bill 1788. As a result of the passage of AB 1322, diphacinone was added to the Restricted Materials list and prohibited for use in all areas of the state except for specific exceptional uses and sites. Specific requirements for rodenticide applicators using diphacinone are described, along with exceptions to restrictions, as well as other related regulatory requirements for rodenticide users.