Here we describe procedures for the selection of diploid Schizosaccharomyces pombe. ade6-M210/ade6-M216 heteroallelic complementation is widely used to select for Ade⁺ diploids. Such diploids will readily sporulate when starved of nitrogen. For some investigations, stable diploids are preferable (e.g., for genetic complementation tests), and in these cases mating an h⁻ strain with an h⁹⁰ mat2-Pi-102 strain can be used to prevent sporulation. When ade6-M210/ade6-M216 mutations impact on, or show synthetic interactions with, the gene of interest, two different auxotrophic markers can be used to select complementation.