UCSF924 (Compound 9-6-24; ZINC000091726127) is a selective, high-affinity dopamine D4 receptor (DRD4) partial agonist (Ki = 3 nM for human D4) with a 7.4-fold bias toward arrestin recruitment over Gαi (Gαi/0; Gi/G0) signaling activation with respect to quinpirole. UCSF924 exhibits no detectable affinity for D2, D3 or the F261V/L328F D4 mutant and no agonist activity toward a panel of 320 nonolfactory GPCRs even at a high concentration of 1 µM. The UCSF924 structure analog UCSF924NC (Comound 9-6-16; ZINC000091707446) is the recommended negative control compound with a 1/2500-fold reduced D4 affinity.