Antibodies directed against Histone post-translational modifications are essential research reagents in chromatin biology. However, they suffer from variable properties and insufficient documentation of quality. In this review paper we evaluate and update the quality criteria for these reagents. In addition, we discuss in detail the advantages and pitfalls of using antibodies and recombinant reading domains. We show that reading domains provide key advantages, such as consistent quality and recombinant production, but the future will tell if this emerging technology keeps its promises.