Glutens, the storage proteins in wheat grains, are a major source of protein in human nutrition. The protein composition of wheat has therefore been an important focus of cereal research. Proteomic tools have been used to describe the genetic diversity of wheat germplasms from different origins at the level of polymorphisms in alleles encoding glutenin and gliadin, the two main proteins of gluten. More recently, proteomics has been used to understand the impact of specific gluten proteins on wheat quality. Here we review the impact of proteomics on the study of gluten proteins as it has evolved from fractionation and electrophoretic techniques to advanced mass spectrometry. In the postgenome era, proteomics is proving to be essential in the effort to identify and understand the interactions between different gluten proteins. This is helping to fill in gaps in our knowledge of how the technological quality of wheat is determined by the interaction between genotype and environment. We also collate information on the various storage protein alleles identified and their prevalence, which makes it possible to infer the effects of wheat selection on grain protein content. We conclude by reviewing the more recent use of transgenesis aimed at improving the quality of gluten.