Combining the techniques of direct excitation of overtone vibrations and time resolved spectroscopic detection permits detailed measurements of the vibrational and rotational relaxation of highly vibrationally excited molecules. Using this technique, we have measured vibrational and rotational relaxation in HF(v = 3,4,5) between 300 K and 650 K and have compared these results to various theoretical calculations. Using laser double resonance to probe individual rotational states, we find phenomenological rotational relaxation rate constants which decrease montonically with rotational energy change in the vibrationally excited molecule, and we have directly measured the vibrational relaxation rate constants for v = 1 and v = 2 as well as made a preliminary estimate of the (surprisingly small) fraction of the relaxation which goes by vibration-to-vibration energy transfer.