Histone posttranslational modifications (PTMs) contribute to transcriptional regulation and generate in combination a “histone code,” which is largely conserved among organismal kingdoms. By binding to specific PTMs, histone reader proteins act as molecular interpreters of the histone code. These proteins play a crucial role in gene regulation and chromatin structure by recruiting other proteins to the chromatin or blocking histone-modifying enzymes from accessing chromatin. Revealing the specificity of histone readers is, therefore, fundamental to understanding their function in gene regulation. Here, we describe a protocol to identify the binding specificity of histone readers to PTMs using histone peptide arrays and in vitro pull-down assays.