This review summarizes the recent (from year 2000) advancements in the interphase tailoring of fiber-reinforced polymer composites. The scientific and technological achievements are classified on the basis of the selected strategies distinguishing between i) interphase tailoring via sizing/coating on fibers, ii) creation of hierarchical fibers by nanostructures, iii) fiber surface modifications by polymer deposition and iv) potential effects of matrix modifications on the interphase formation. Special attention was paid to report on efforts dedicated to the creation on (multi)functional interphase in polymer composites. This review is round up by listing current trends in the characterization and modelling of the interphase. In the final outlook, future opportunities and challenges in the engineering of fiber/matrix interphase are summarized.