A new in situ polymerization method is discussed wherein monomers of the major component are polymerized in the presence of a preformed thermotropic liquid crystalline polymer (LCP). Poly (p -oxybenzoate- co-p -phenyleneisophthalate) (HIQ) was chosen for this study. HIQ is well known to have a narrow process window and to be difficult to process reproducibly, both drawbacks for a commercial product. An in situ polymerization of the HIQ monomers in the presence of a fully polymerized LCP, such as poly(4-oxybenzoate-co-6-oxy-2-naphthoate) (CO) results in the "CO-HIQ" in situ blend. The in situ blend exhibited reduced biphasic morphology and was more homogeneous than was HIQ. The glass fiber-filled CO-HIQ resin also featured improved melt flow and more reproducible mechanical properties than those of HIQ. The in situ blends were characterized by optical microscopy, H-1-NMR, and melt rheology. The effect of the LCP level on the morphology of the in situ blend is discussed.