Ground settlement causes extensive damage worldwide and has a significant impact on engineering design and mitigation. Identification of settlement origins can be challenging and expensive. The ability to identify the likely cause(s) of settlement using a rapid forensic analysis can reduce field time and constrain site investigation strategies, thereby reducing costs. The Rapid Settlement Diagnostic System (RSDS) has been developed as a preliminary tool for efficiently identifying likely sources of geology-related settlement. The four-step questionnaire in Microsoft Excel format enables personnel to quickly isolate potential causes of settlement using initial site observations and basic site knowledge. The first step distinguishes whether the observations involve geology-related settlement or another issue, such as structural instability. The second and third steps narrow down the list of likely settlement causes for the area of concern through a series of questions regarding the site conditions with answer options of “yes,” “no,” or “unknown.” The fourth step provides a final calculation and rank indicating the most likely cause(s) of settlement that should be investigated further through a detailed site investigation. The RSDS has been tested using historic cases of settlement with known causes to evaluate the effectiveness and ease of use of the tool. The results from the validation process have been used to revise the questions and scoring system in the RSDS in order to improve the usefulness and clarity of the tool.