The effects of roughness were considered as part of a NATO Advanced Vehicle Technology effort titled "Non-Equilibrium Turbulent Boundary Layers at High Reynolds Numbers" (NATO AVT-349). This paper comments on the current state of understanding of the flow physics and modeling efforts to predict rough-wall boundary layer behavior. Outer layer similarity to smooth wall flows and Reynolds number effects are discussed for zero, favourable, and adverse pressure gradients based on the results of experiments and numerical simulations. Various types of modeling are considered including Reynolds averaged Navier-Stokes (RANS) models with different roughness and turbulence models, wall-modeled large eddy simulations (WMLES), and resolvent models. Current needs and gaps in present understanding are discussed along with recommendations for future experiments and computations.