Matrix polymerization can be viewed as an intriguing procedure for the preparation of homogeneous blends that are other-wise difficult or practically impossible to prepare. Poly(p-phenylene-terephthalamide) has been synthesized by direct polycondensation in the presence of poly(N-vinylpyrrolidone) or poly(4-vinylpyridine) as polymer matrices. The molecular weight effect of the latter polymers on the intrinsic viscosity of the aramid has been investigated. Poly(p-phenyleneterephthalamide), characterized by intrinsic viscosity as high as 14.2 dL/g, is obtained when high molecular weight poly(N-vinylpyrrolidone) is used. The intimate composites formed in situ have been characterized by solidstate NMR. The parent and daughter polymers in the composite present the same proton T, relaxation times in the rotating frame, and this value differs from that of the neat polymers; this result demonstrates the intimacy of the blend at the level of a few nanometers.