Abstract: Ants are the world's premier eusocial organisms and they have assumed pivotal ecological roles in many terrestrial communities. A well resolved and robustly supported phylogeny of the ants is needed to better understand many facets of their ecology and evolution. We report on a new project designed to clarify the phylogenetic relationships of the major lineages of ants. Funded by the Us National Science Foundation under the AToL (Assembling the Tree of Life) program, this project runs for five years and involves collaborators from the University of California at Davis, the California Academy of Sciences, and the Smithsonian Institution. In the first year (2004 - 2005) of the Ant AToL grant we have focused our efforts on developing a multi-gene molecular data set and assembling a selection of appropriate taxa. A preliminary analysis, based on ~5.8 kb of sequence data from seven nuclear genes and ~100 exemplar species, reveals a number of novel findings and contradicts some earlier conclusions derived from morphological data. Nearly all of the 21 extant ant subfamilies recognized in a recent morphology-based classification of ants (Bolton 2003) appear to be monophyletic, but our evidence suggests that only two of the six supra-subfamilial groups (dorylomorphs and myrmeciomorphs) are monophyletic. We find strong support (parsimony and likelihood bootstrap 100 %, Bayesian posterior probability 1.00) for a group, here termed the "formicoid clade", which contains all extant ants except Agroecomyrmecinae, Amblyoponinae, Leptanillinae, Paraponerinae, Ponerinae, and Proceratiinae. Relationships among these early diverging (non-formicoid) ants are not well resolved. This work is ongoing, and a more comprehensive account and analysis with additional taxa and new molecular data will be completed at the year's end.