The critical temperature for the attractive Hubbard model on a square lattice is determined from the analysis of two independent quantities, the helicity modulus ρ s and the pairing correlation function P s. These quantities have been calculated through quantum Monte Carlo simulations for lattices up to 18× 1 8, and for several densities, in the intermediate-coupling regime. Imposing the universal-jump condition for an accurately calculated ρ s, together with thorough finite-size scaling analyses (in the spirit of the phenomenological renormalization group) of P s, suggests that T c is considerably higher than hitherto assumed.