The purpose of this study was to examine the influence of Assisted Cycling Therapy (ACT) on depression in older adults with Down Syndrome (DS). We predicted that older adults with Down Syndrome would see an improvement in their depressive symptoms after ACT and Voluntary Cycling (VC). However, we predicted there would be a greater improvement in depressive symptoms after ACT in comparison to VC. Depression was measured using a modified version of the Children's Depression Inventory 2 (CDI 2) due to the low mental age of our participant population. Twenty-one older adults with DS were randomly assigned to one of three interventions, which took place over an eight-week period of time. Eleven older adults with DS completed the ACT intervention, which is stationary cycling on a recumbent bicycle with the assistance of a motor to maintain a cadence at least 35% greater than the rate of voluntary cycling. Nine participants completed the voluntary cycling intervention, where they cycled at a cadence of their choosing. One participant composed our no cycling control group. No intervention group reached results that achieved a conventional level of significance. However, there was a trend for depression to increase after 8 weeks throughout all three intervention groups. We did see a slightly slower regression of depression in the ACT group than the VC and control. Our results were discussed with respect to social and cognitive factors relevant to older adults with DS and the subjective nature of the CDI2. This study brings attention to the lack of accurate measures and standardized research methods created for populations with intellectual disabilities in regards to research.