ABSTRACT.Single Step methods combine pedigree relationships and marker genotypes in a single conceptual and streamlined framework based on extending animal model BLUP to include marker genotypes. The extension can be done because genotypes at markers follow covariances described by the pedigree. This results in a relationship matrix that combines pedigree and markers, called H. Fitting H-1 in Henderson?s Mixed Model Equations gives the Single Step Genomic BLUP, which is a single estimator of breeding values that includes all available information. It is easily generalizable to multiple trait and many different models, including Bayesian regressions. Extensions to crosses are largely untested and may need theoretical developments. Single step is increasingly used in poultry breeding, for its ease of use, generality, and better accuracy than any competing method. Some results in poultry are discussed.