  We add fundamental flavors to N=2 Chern-Simons-matter theories living on M2
branes probing a Calabi-Yau four-fold singularity. This is dual, in the 't
Hooft limit described by IIA string theory, to the introduction of
supersymmetric D6 branes wrapping AdS4 and a 3-cycle of the internal manifold.
The resulting Chern-Simons theories remain conformally invariant, corresponding
to the fact that the D6 branes lift to pure geometry in M-theory. The
determination of the moduli space relies crucially on the 1-loop contributions
to charges and OPE's of monopole operators in these field theories. The general
picture is determined for non-chiral and chiral flavors, and is illustrated in
several examples.
