We investigate the finite-temperature behavior of (2 + 1)-dimensional SU(3) lattice gauge theory by Monte Carlo methods. A continuous and presumably second-order deconfining phase transition is found at a critical temperature Tc. Estimates are made for various critical exponents. The behavior of higher-representation Polyakov loops is studied near the phase transition. In the high-temperature phase we compare the internal energy density with expectations based on a non-interacting gas of bosons.