Diffusive photopolymers are an area of intense recent materials development, spurred by interest in holographic data storage, display holography, and custom diffractive optical elements, among other applications. This review examines a range of photopolymer formulations of academic and commercial interest, and places their design strategies in context via quantitative analysis of the recording fidelity, maximum refractive index change and the degree to which they achieve this limit. Finally, this analysis is extended to estimate the scope of achievable future performance improvements. (c) 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1021-1035.