Metal matrix composites provide a degree of design flexibility that is not attainable with homogeneous materials. As such there is extensive research on MMC design which includes topics such as tailoring of reinforcement size, morphology and material composition, to name a few. Recently, trimodal composites, consisting of coarse grain matrix regions and ultrafine grain matrix regions embedded with hard ceramic particles, represent an interesting intersection of MMCs with nanostructured metals. In this presentation we review the processing, microstructure evolution, and mechanical behavior of trimodal composites. Relevant length scales range from nanoscale through macroscale, with significant emphasis on designing and understanding the role of interfaces, using both in-situ and ex-situ techniques. Performance enhancements provided by trimodal composites include not only significant increases in strength, but more importantly the ability to selectively design for desired strength and ductility combinations. Future opportunities to expand the applications for these materials will also be discussed.