  Phenomenological explorations of heterotic strings have conventionally
focused primarily on the E8xE8 theory. We consider smooth compactifications of
all three ten-dimensional heterotic theories to exhibit the many similarities
between the non-supersymmetric SO(16)xSO(16) theory and the related
supersymmetric E8xE8 and SO(32) theories. In particular, we exploit these
similarities to determine the bosonic and fermionic spectra of Calabi-Yau
compactifications with line bundles of the non-supersymmetric string. We use
elements of four-dimensional supersymmetric effective field theory to
characterize the non-supersymmetric action at leading order and determine the
Green-Schwarz induced axion-couplings. Using these methods we construct a
non-supersymmetric Standard Model(SM)-like theory. In addition, we show that it
is possible to obtain SM-like models from the standard embedding using at least
an order four Wilson line. Finally, we make a proposal of the states that live
on five branes in the SO(16)xSO(16) theory and find under certain assumptions
the surprising result that anomaly factorization only admits at most a single
brane solution.
