A 1-D two-phase model with nonuniform catalyst loading along the channel length is used to present a detailed analysis of light-off behavior and cumulative emissions in a catalytic monolith in which an exothermic reaction occurs. The influence of important design parameters such as the washcoat thickness, solid conductivity, channel geometry, and catalyst distribution along the channel on the transient time and cumulative emissions is analyzed. An analytical light-off criterion for the case of nonuniform catalyst loading is proposed, with the help of which we can determine the nature of ignition (front-end, middle, or back-end ignition). It is found that, for the wall reaction case, nonuniform catalyst loading with two zones of catalyst with more catalyst at the inlet favors front-end ignition and reduces the transient time as well as the cumulative emissions. Though high solid conduction is better for steady-state designs, better transient and equivalent steady-state performances can be obtained for finite solid conduction by distributing the catalyst appropriately. As can be expected, washcoat diffusion has a profound influence on light-off and defines a critical value of catalyst loading below which front-end light-off does not occur. For catalyst loading exceeding this critical value, there is a maximum value of washcoat thickness (corresponding to a washcoat Thiele modulus of 0.5 at inlet fluid temperature) below which light-off is not influenced by washcoat diffusion. Increasing the washcoat thickness beyond this critical value has no effect on the transient time or cumulative emissions. There is a range of catalyst loading in which uniform distribution leads to the optimal design, while outside this range, the optimal design corresponds to having more catalyst at the front. It is also found that parallel-plate or rectangular channel geometries with high aspect ratios lead to better transient and good steady-state performances. Finally, we show that an optimally designed monolith with proper catalyst distribution, solid conductivity, channel geometry and dimensions, and washcoat can reduce cold-start emissions substantially compared to the standard case.