For several years the MULAN collaboration has been pursuing the ambitious goal of a 1 ppm determination of the muon lifetime. This experiment has been motivated by recent theoretical improvements in extracting the Fermi coupling constant GF, from the measured muon lifetime, τμ, which have reached the 1 ppm level in the theoretical error. The coupling constant GF is an essential parameter of the Standard Model. Its uncertainty limits the precision for Standard Model predictions and interpretations. Progress and highlights of the experiment will be discussed.