A comprehensive study of the forced-flow chemical vapor infiltration process is presented. A rigorous mathematical model accounting for mass transport (by bulk and Knudsen diffusion and viscous flow), chemical reaction, and structure evolution is formulated for the process. We also develop a simplified model for the case in which transport is controlled by viscous flow and use it to derive analytical results of the parametric sensitivity of the process. The effects of pressure, structure, flow rate, thermal gradient, reaction reversibility, and periodic flow reversal on the performance of forced-flow chemical vapor infiltration are examined using both the rigorous and the simplified model. The results show that for a given set of operating conditions, there is an optimal flow rate that produces the best deposition uniformity in the preform. However, even for operation with the optimal flow rate, forced-flow chemical vapor infiltration can outperform the isobaric process only for large enough values of pressure and pore size. Another interesting result is that periodic flow reversal can lead to a dramatic improvement of the deposition uniformity, even in the absence of a thermal gradient.