We construct the Neveu-Schwarz sector of heterotic string field theory using
the large Hilbert space of the superghosts and the multi-string products of
bosonic closed string field theory. No picture-changing operators are required
as in Wess-Zumino-Witten-like open superstring field theory. The action
exhibits a novel kind of nonpolynomiality: in addition to terms necessary to
cover missing regions of moduli spaces, new terms arise from the boundary of
the missing regions and its subspaces. We determine the action up to quintic
order and a subset of terms to all orders.Comment: 15 pages, no figures, LaTeX2e; v2: minor cosmetic change