Putting green firmness is a key playability factor in the game of golf. Greens that are too soft reward poorly struck approach shots, while a green that is too hard may result in unanticipated ball movement. The intent of this research is to develop guidelines for golf course managers that will enable them to provide high quality putting surfaces in a resource-efficient manner. Previous research has found that a greater soil moisture content results in a softer surface on sand-based root zones. The level of compaction and organic matter content may also influence surface firmness. This study is designed to investigate how soil moisture content, organic matter content and compaction interact to influence putting green firmness. The study is a 3x2x3 factorial, setup as a split block over multiple locations/putting greens with different levels of irrigation applied at the different locations. Each block has three levels of compaction and half of each block is dethatched. All three putting green root zones are brought to saturation, allowed to dry down, and then the different irrigation application rates are initiated. Soil moisture content, surface firmness, turfgrass quality and green speed are being measured throughout each trial. Preliminary results indicate that after the dry down period there is a significant interaction between irrigation and organic matter/thatch control on surface firmness. As the experiment continues it is expected that the interactions will become more significant due to the cumulative effects of the treatments over time.