We discuss the results of recent 3D simulations of first structure formation in relationship to the formation of the first stars. On the basis of a new, high-resolution AMR simulation (spatial dynamic range = 30,000,000), we conclude that the first stars are likely to be massive.

11 pages, 4 figures (see http://logy.harvard.edu/tabel/Homepage/trans.html for color postscripts of Fig. 3.) to appear in "The First Stars", Eds. A. Weiss, T. Abel & V. Hill, Proceedings of the MPA/ESO Workshop, Garching, Germany 4-6 August 1999, (Springer Verlag, Heidelberg)