Genome-wide association studies (GWAS) have become a very popular method for dissecting the genetic basis of complex traits in plants, including wheat. The benefits of GWAS are a relatively detailed mapping resolution and that no population development is required. The surge of interest in GWAS has been fueled by recent developments in genomics that allow for rapid identification of genetic markers. This chapter describes the features of GWAS, including high-density genotyping, phenotyping and GWAS design. The chapter explains the use of GWAS for controlling population structure and familial relatedness, considering the estimation of linkage disequilibrium (LD) and considering issues of research replication and validation. Finally, the chapter looks ahead to future trends in research in this field and includes a detailed case study on genomic regions conferring increased grain weight.