Abstract In this chapter, we discuss how the two different excess pore-pressure-generating mechanisms that are primarily associated with burial affect stresses in different ways. We, and others before us, term these two mechanisms as either “compaction disequilibrium” or “source mechanisms.” Rapid burial rates in association with low permeabilities are attributed to the former, whereas aquathermal expansion, smec- tite/illite diagenesis (or other diagenetic processes), kerogen maturation, and hydrocarbon cracking are examples of the latter. The compaction disequilibrium mechanism is fundamentally different from the source mechanism. In the compaction disequilibrium case, pore-pressure increases are primarily a reaction of the fluid to pore-volume decreases that are a result of increased vertical loading (assuming minimal tectonic stresses). The magnitude of the pressure increase depends on the load increase and the relative magnitudes of the sediment pore-volume and pore-fluid compressibilities. Regardless of the magnitude of the pore-pressure increase, mechanical equilibrium requires that the effective stresses of the sediment increase. As a result, both the horizontal and vertical (effective and total) stresses of a given sediment package increase as its burial depth increases, and pore-pressure increases due to burial are less than the increase in the overburden stress. In the source case, pore-pressure increases are a response to increases in the pore-fluid specific volume. In a source-dominated system, the sediment pore volume increases, and, consequently, the effective stresses decrease. In these cases, the pore pressures increase faster than the effective stresses decrease, and the horizontal and vertical total stresses increase. Because pore volumes increase, the increases in pore pressure can be larger than increases in overburden stress.