The critical density for kaon condensation in ``nuclear star" matter is
computed up to two-loop order {\it in medium} (corresponding to
next-to-next-to-leading order in chiral perturbation theory in free space) with
a heavy-baryon effective chiral Lagrangian whose parameters are determined from
KN scattering and kaonic atom data. To the order considered, the kaon
self-energy has highly non-linear density dependence in dense matter. We find
that the four-Fermi interaction terms in the chiral Lagrangian play an
important role in triggering condensation, predicting for ``natural" values of
the four-Fermi interactions a rather low critical density, ρc<4ρ0.Comment: 12 pages and 2 figures(LaTeX), SNUTP-94-28. The fig. 3 is replaced,
with some changes in the text but the conclusion is not affected by these
change