INTRODUCTIONThe inheritance of mutant phenotypes in Arabidopsis thaliana is most often analyzed in the progeny resulting from crosses between different parents. This article describes genetic strategies for the analysis of mutants. Newly identified mutations can be examined initially using segregation analysis, followed by backcrossing and cosegregation for removal of extraneous mutations and assessment of pleiotropy. Confirmation that a phenotype of interest results from a given mutation can be achieved via complementation testing, which is also used to determine allelism of recessive mutations. The construction of double mutants is useful in the study of signal transduction and metabolic pathways. Considerations for the use of double homozygotes and their identification in the F₂ and F₃ generations are described at the end of this article.