With increasing interest in higher throughput techniques applied to basic research we have demonstrated the ability to detect and characterise activation of GPCRs in an assay which is fully scaleable. Monitoring changes in intracellular calcium with fluorescent dyes using FLIPRTETRA® is a powerful assay for G-Protein Coupled Receptors and is widely used in primary screens. The imaging of beta arrestin-mediated GPCR desensitization with Transfluor® using imagers like ImageXpressTM is anenabling tool for the functional analysis of orphan GPCRs and GPCRs with weak calcium signaling. Using the Angiotensin receptor and a novel red calcium dye, we previously demonstrated that the advantages of both Transfluor and FLIPR® can be obtained at once in a convenient combination assay using the same cells in the same well. The assay is homogenous and the Transfluor assay is read on plates fixed immediately following the calcium flux assay. After fixing, the plates can be stored for extended periods of time before imaging therefore uncoupling primary and secondary screen activities. In this study, we looked for agonists and antagonists of the Angiotensin receptor in the LOPAC1280TM library and were able to quickly characterize the FLIPR hits by observing the Transfluor response in the same cells. For example, non-specific calcium flux caused by compounds targeting endogenous receptors or calcium signalling independent of target receptor could be qualified with Transfluor; which is independent of calcium signaling and requires over-expression of the target receptor. These experiments also further validate the equivalent pharmacology of the receptor in FLIPR and Transfluor assays. For high throughput screens, this assay should both help decrease cost and increase speed of the compound characterization process, whilst the imaging of beta arrestin-mediated GPCR desensitization with Transfluor® provides an ideal first step in smaller screens.