  We study the effect of spin anisotropies on a frustrated quantum
antiferromagnet using the J_1-J_2^{XXZ} model on the square lattice. The T=0
and finite-T phase diagrams of this model are obtained utilizing spin-wave
theory, exact diagonalization, and quantum Monte Carlo. We find that
anisotropic frustration tends to stabilize XY- and Ising-like ordered phases,
while the disordered spin-liquid phase is restricted to a small region of the
phase diagram. The ordered phases are separated by first-order transitions and
exhibit a non-trivial reentrance phenomenon.
