We are developing a compact, light-weight coincidence-detection probe comprised of a 1 cm3 CsI(Tl) scintillator, Si photodiode and hybrid preamplifier. We characterized performance of a prototype probe in bench tests. The characterization consisted of: point source response vs. distance, energy spectra, and coincidence time constant measurements. Coincidences from 111In are present in a well-isolated sum peak at 416 keV in the energy spectrum. The energy resolution of the sum peak is 11% Full Width Half Maximum (FWHM). The point source response decreases as the fourth power of the distance from the source. We also compared detector performance with that of a single-gamma-detecting probe in simulations using a numerical torso phantom into which biodistribution data for an 111In-labeled monoclonal antibody had been entered. The Hotelling trace value (HTV) was used as the figure of merit. The coincidence-detection probe has an order of magnitude better Hotelling trace value than the single-gamma-detecting probe in the simulations. The coincidence-detection probe shows promise for practical intraoperative tumor localization with 111In-labeled radiopharmaceuticals.