Protein tyrosine phosphatase-γ (PTP-γ) is a receptor-like PTP whose biological function is poorly understood. A recent mouse PTP-γ genetic deletion model associated the loss of PTP-γ gene expression with a potential antidepressant phenotype. This led the authors to screen a subset of the Bristol-Myers Squibb (BMS) compound collection to identify selective small-molecule inhibitors of receptor-like PTP-γ (RPTP-γ) for use in evaluating enzyme function in vivo. Here, they report the design of a high-throughput fluorescence resonance energy transfer (FRET) assay based on the Z'-LYTE technology to screen for inhibitors of RPTP-γ. A subset of the BMS diverse compound collection was screened and several compounds identified as RPTP-γ inhibitors in the assay. After chemical triage and clustering, compounds were assessed for potency and selectivity by IC(50) determination with RPTP-γ and two other phosphatases, PTP-1B and CD45. One hundred twenty-nine RPTP-γ selective (defined as IC(50) value greater than 5- to 10-fold over PTP-1B and CD45) inhibitors were identified and prioritized for evaluation. One of these hits, 3-(3, 4-dichlorobenzylthio) thiophene-2-carboxylic acid, was the primary chemotype for the initiation of a medicinal chemistry program.