A series of oxazoline-modified styrene-acrylonitrile (SAN) copolymers was prepared through the reaction of amino alcohols onto preformed SAN copolymers. Consequently, a variety of reactive copolymers were synthesized. The major focus of this study was to examine the influence of reaction conditions, i.e., the nature of the catalyst and amino alcohol structure, on reactivity. The ability to incorporate oxazoline groups onto preformed polymers is dependent on whether homogeneous reaction conditions are met. For example, the use of nonreactive solubilizing agents, i.e., cosolvent, is effective. However, optimum conditions are obtained when the catalyst is completely soluble in the reaction mixture containing the amino alcohol and SAN copolymer. With these restrictions, zinc stearate is quite effective. Our results show that controlled and reproducible levels of oxazoline can be incorporated (typically at a rate of 2 mol %/h) up to high levels. These results are general and therefore are applicable to a wide variety of nitrile-containing polymers.