Tremor is a common symptom of multiple sclerosis (MS) that has debilitating effects on occupational performance and well-being. Tremor is complex, and a valid and reliable assessment tool that takes a multidimensional approach is needed to guide intervention decisions. A new assessment instrument, the Multidimensional Assessment of Tremor (MAT), was designed to measure the severity and functional impact of tremor in people with MS. This study was conducted to introduce this new tool and examine its reliability, validity, and clinical utility. Two clinicians tested the MAT and completed a questionnaire on its clinical utility. During an initial visit, 10 study participants with MS were administered the MAT, which was independently scored by two researchers to determine its inter-rater reliability. Four other tools commonly used to assess tremor were also administered to evaluate the MAT's criterion validity. During a second visit, the MAT was administered a second time to ascertain its test-retest reliability. Study participants demonstrated mild-to-severe tremor with marked functional difficulties. The MAT's inter-rater reliability and test-retest reliability were excellent, while its criterion validity ranged from poor to good. The clinicians, participants, and researchers found the clinical utility of the tool to be good. The MAT offers therapists a clinically useful, evidence-based, and multidimensional tool for evaluating tremor in MS.