Longer life expectancy, rapid population growth, and low exercise-participation rates of adults 65 and older justify the need for better understanding of older adults' exercise behavior. The objectives of this focus-group study were to determine barriers to the exercise behavior of older adults. Six focus groups, three with exercisers and three with nonexercisers, were conducted at various sites throughout Rhode Island. The majority (n = 57) of the 66 individuals who participated were women, and all stated that they were 65 and older. Results from the focus-group data identified 13 barriers to exercise behavior. The most significant barriers mentioned by nonexercisers were fear of falling, inertia, and negative affect. Exercisers identified inertia, time constraints, and physical ailments as being the most significant barriers to exercise. Implications from these focus-group data can be useful in the development of exercise interventions for older adults, which could increase exercise participation.