The work contains the doctoral dissertation the author presented at Universite Catholique de Louvain in January, 2000. The first two chapters deal with extensions of results of Quillen, Anick, Scheerer-Tanre and Halperin on the homology of differential graded Lie algebras and their universal enveloping algebras. The last two chapters deal with characteristic zero loop space homology of two-cones (cofibers of maps between wedges of spheres) and fat wedges of spheres, respectively. Numerous examples are discussed in careful detail. The topic may interest rational homotopists, Lie algebraists and, possibly, some group theorists.