Children with Down Syndrome face major challenges in maintaining active social interaction. HCI research has well explored the design of computer-aided systems to support education for teachers and therapists, but comparatively less work has been considered in the case of social behavior learning for Down Syndrome children and their caregivers. Many challenging behaviors originate from misunderstanding DS children’s emotions, body language, and verbal expressions. To better investigate the barriers to maintaining active social interaction for DS children and their caregivers, we conducted a social activity with an organization providing therapeutic treatment for DS children. Situated in a co-designed drama rehearsal activity for acting, storytelling, and socializing, our field observations and semi-structured interviews with family caregivers, therapists, and volunteers have illustrated certain behavior characteristics of DS children that may hinder communication and understanding with their caregivers. Based on this field study, we are contributing a nuanced understanding of the behavior issues of DS children during social interactions. Furthermore, we are proposing a collaborative partnership model to engage both non-professional and professional caregivers in developing a safe, effective, flexible, caring mode to allow DS children to be more self-independent in broader social contexts. Finally, we have brought forward the suggestion that the visual analytics technique can be used as a novel mediated form of assistive technology to support social behavior learning and personalized intervention.