Polymer blending is an alternative approach to obtaining new materials with unique or desirable properties based on those commercially available polymers rather than to design and synthesize total novel polymers [1]. Since thermotrolpic liquid crystalline polymers (TLCPs), which have dis-played good thermal and mechanical properties and dimensional stability, especially excellent melting processability, were developed about 20 years ago, this new class of high performance polymers has receiived significant attention. Not only have many TLCPs with various chemical structures been synthesized, but some related research fields have also rapidly devel-oped [2, 31. Blending TLCPs with conventional thermoplastic polymers is one of these branches [4]. Polymer blends involving TLCPs as one of the components are termed “in situ composites” [5]. The purpose of preparing such an “in situ composite” is mainly to improve the processability of the thermoplastic matrix with the aid of a small amount of TLCP, due to its relatively low melt viscosity, and also to reinforce the matrix or to enhance its dimensional stability simultaneously. This summary is an attempt to provide a brief picture of recent developments in this field. The general blending of polymer pairs; the mixing, blending, and processing methods or some specially developed techniques; the blend morphology and rheology features and characterizations; and the thermal and mechanical properties, especially for some important factors that directly affect the efficiency of the reinforcement derived from the TLCP, will be discussed in detail.