Scientists have developed methods to isolate and purify photosystem II reaction center complexes from plants. They have described procedures for isolating 6- and 5-chlorophyll complexes, including a simpler method for 6-Chl and a detailed procedure for 5-Chl. Additionally, a rapid procedure that yields larger amounts of less pure 6-Chl material has been outlined. Criteria for assessing the purity of the preparations are provided, along with discussions on the advantages and disadvantages of each isolation method.