Bromodomains recognize acetylated lysine residues and recruit regulatory complexes to acetylated nucleosomes, thereby controlling chromatin structure and gene expression. The isolated individual or tandem bromodomains of BRD2 and BRD4 bind acetylated histone tails, which couples histone acetylation marks to the transcriptional regulation of target promoters. Small molecule inhibitors of bromodomain interactions hold promise as useful therapeutics for human disease. Cayman's BRD4 bromodomain 1 TR-FRET Assay Kit is a homogeneous, TR-FRET assay method amenable to rapid characterization of inhibitors of bromodomain/acetylated peptide interaction in a high throughput format. This screening assay kit is robust, displaying a Z' >0.6.