  We study the dynamics of 2+1 dimensional theories with ${\cal N}=1$
supersymmetry. In these theories the supersymmetric ground states behave
discontinuously at co-dimension one walls in the space of couplings, with new
vacua coming in from infinity in field space. We show that the dynamics near
these walls is calculable: the two-loop effective potential yields exact
results about the ground states near the walls. Far away from the walls the
ground states can be inferred by decoupling arguments. In this way, we are able
to follow the ground states of ${\cal N}=1$ theories in 2+1 dimensions and
construct the infrared phases of these theories. We study two examples in
detail: Adjoint SQCD and SQCD with one fundamental quark. In Adjoint QCD we
show that for sufficiently small Chern-Simons level the theory has a
non-perturbative metastable supersymmetry-breaking ground state. We also
briefly discuss the critical points of this theory. For SQCD with one quark we
establish an infrared duality between a $U(N)$ gauge theory and an $SU(N)$
gauge theory. The duality crucially involves the vacua that appear from
infinity near the walls.
