Flavor and quark mass dependence of QCD thermodynamics

We calculate the transition temperature in 2 and 3-flavor QCD using improve d gauge and staggered fermion actions on lattices with temporal extent N-r = 4. We find T-c = 173 (8) MeV and 154 (8) MeV for n(f) = 2 and 3, respecti vely. In the case of 3-flavor QCD we present evidence that the chiral criti cal point, i.e. the second order endpoint of the line of first order chiral phase transitions, belongs to the universality class of the 3d Ising model .