We report results of multi-transition observations and modeling of the hydrocarbon ring molecule cyclopropenylidene (C\sb3H\sb2). From a survey of the 1\sb{10}-1\sb{01} (18 GHz) and 2\sb{12}-1\sb{01} (85 GHz) transitions in the Galaxy, we have found C\sb3H\sb2 present in a variety of sources including cold, dark clouds, giant molecular clouds, the envelope of a carbon star, and diffuse clouds. Up to 10 transitions of C\sb3H\sb2 ranging in wavelength from 1.3 cm to 1.3 mm were observed in the dark clouds L1498, L134N, B335 and toward several positions in TMC-1. The Large Velocity Gradient (LVG) approximation was used to model the observations. Optical depth values of C\sb3H\sb2, estimated from C\sp{13}C\sb2H\sb2 observations, are necessary to constrain the results since the range in excitation energies of the observed C\sb3H\sb2 transitions does not contrast sufficiently. The molecular hydrogen density in TMC-1 is estimated to be 3.7 × 10\sp4 cm\sp{-3}, while the fractional abundance of C{\sb3}H\sb2 relative to H\sb2 is 5.7 × 10\sp{-9}. Previous estimates assuming LTE conditions overestimate the abundance of C\sb3H\sb2. The abundance in the ridge component in Orion is estimated to be approximately 8 × 10\sp{-10} cm \sp{-2}. Gas phase chemical models can reproduce the high C\sb3H\sb2 abundance found in dark clouds under assumptions such as steady state conditions with (C) / (O) / 3˘e 1.0, conditions of earlier evolutionary time, or \u27optimistic\u27 rate coefficients. However, large deuteration ratios (0.05 to 0.15) create difficulties for gas phase models
