Using small molecules in polymer matrices is common in applications such as (i) plasticizing polymers to modify the glass transition and mechanical properties and (ii) dispersion of photoactive or electroactive small molecules in polymer matrices in organic-electronic devices Aggregation of these small molecules and phase separation leading to crystallization often cannot be morphologically controlled. If these are designed with self-assembling codes such as hydrogen bonding or aromatic interactions, their phase separation behavior would be distinctly different. This review summarizes the studies on morphologies in such situations, such as (i) sub-surface assembly in polymer matrices, (ii) controlled polymerization-induced phase separation to create polymer blends, (iii) using the polymer to direct the assembly of small molecules in liquid crystalline devices, (iv) functionalizing a polymer with self-assembling small molecules to cause organo-gelation which the polymer itself would not by itself, and (v) using such systems as templates to create porous polymer structures. Organic-inorganic hybrids using polymers as templates for nanostructures and imprinted porous membranes is an emerging area. Since self-assembly is one of the dominating area of research with respect to both small molecules, polymers as well as the combination of the two, this review summarizes the studies on the aforementioned topics. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 451-478