Sphingosine 1-phosphate (S1P) is a bioactive phospholipid released by activated blood platelets that serves to influence heart rate, coronary artery caliber, endothelial integrity, lung epithelial integrity, and lymphocyte recirculation through five related high affinity G-protein coupled receptors. S1P4 receptor is coupled to Gαi and Gαo G proteins and activates extracellular signal-regulated kinases (ERK) mitogen-activated protein kinases (MAPK) and Phospholipase C (PLC) downstream pathways. Inhibition of lymphocyte recirculation by nonselective S1P receptor agonists produces clinical immunosuppression preventing transplant rejection, but is associated with transient bradycardia. Understanding the contribution of individual receptors has been limited by the unavailability of selective agonists or antagonists for the 5 receptor subtypes. The Scripps Research Institute Molecular Screening Center (SRIMSC), part of the Molecular Libraries Probe Production Centers Network (MLPCN), previously identified an S1P4 agonist probe, ML178, which has submicromolar potency and is completely selective against the five other S1P receptor family members; but has non-classic structure and flat medicinal chemistry. The SRIMSC reports here ML248, a novel compound with potent and selective S1P4 receptor agonist activity that is amenable to further medicinal chemistry optimization. ML248 was identified by high-throughput screening using a cell-based Tango™-format assay. ML248 activates S1P4 receptor with a half maximal effective concentration (EC50) of 37.7 nM–79.1 nM, and is inactive as an agonist against other members of the receptor family, with EC50s > 25 μM against S1P1, S1P2, and S1P3 receptors, and an EC50 of 2.1 μM against the S1P5 receptor. ML248 is inhibited by an S1P4 receptor-selective antagonist, inactive for agonism in the presence of ≥ 3.7 nM selective antagonist and is nontoxic to U2OS cells, with a CC50 of > 10 μM. ML248 was submitted to Ricerca Biosciences LLC., target profiling against a panel of receptors, transporters, or ion channels; the data suggest that ML248 is generally inactive against a broad array of off-targets and does not likely exert unwanted effects.