There is a need to engage people with chemistry and to facilitate learning about chemistry in both nonformal and informal learning environments. A variety of platforms have been used to achieve this, including science festivals, summer camps, and so on. The events are voluntary, and participants need to be motivated independently to engage. The aim of the study was to systematically investigate what motivates children and their parents to participate in a specific nine-month chemistry course designed for families. The findings apply to a variety of chemistry outreach events. The present study was conducted with 342 participating parents and children who voluntarily enrolled in a chemistry family learning course which consisted of multiple events. Motivation to participate was investigated using a questionnaire, which was administered directly before participation. Data were analyzed using descriptive and inferential analyses. Children and parents displayed similarities and differences regarding their motivation to participate. They both assigned the highest values to the dimensions of "research and experimentation," "individual learning and pursuing interests," "social enjoyment," and "social learning." However, there are striking differences in the order of these dimensions for each group. As such, children and parents should be regarded as two distinct target audiences for a chemistry family learning course. It might also be useful for other recurring programs to know the participants' motivation to participate. In this study, it was strongly indicated that the course was a way to reengage adults with chemistry through their role as parents. This finding might also change the perspective on parents as participants in other chemistry outreach events.