Grain size and temperature significantly influenced intergranular pressure solution, quartz cementation, and porosity evolution in the quartzose Hartshorne Sandstone (Middle Pennsylvanian) of the Arkoma Basin. Among samples from each locality, a negative, linear relationship exists between mean grain size and volume of quartz dissolved by intergranular pressure solution. In contrast, a generally positive relationship exists between mean grain size and volume of quartz cement, although considerable variability exists in this relationship. A positive relationship also exists between mean grain size and porosity. Intergranular pressure solution directly reduced minus-cement porosity by causing tighter packing of detrital grains; it thereby controlled volumes of both cement and primary porosity. For this reason, little primary porosity is preserved in pressolved, finer-grained sandstones even though they contain small absolute volumes of quartz cement. Appreciably more primary porosity may be retained by unpressolved, coarser-grained sandstones even though they contain larger absolute volumes of quartz cement. Thermal maturity increases eastward across the basin, and is the result of elevated temperatures associated with Mesozoic rifting and intrusive events in the Mississippi embayment. More intergranular pressure solution, less quartz cement, and less porosity are evident in areas of higher thermal maturity. Primary porosity tends to be preserved preferentially in areas of lower thermal maturity even though the absolute volume of quartz cement is generally higher.--Modified journal abstract.