Social avoidance is a core phenotypic characteristic of fragile X syndrome (FXS) that has critical cognitive and social consequences. However, no study has examined modulation of multiple social avoidant behaviors in children with FXS. In the current study, we introduce the Social Approach Scale (SAS), an observation scale that includes physical movement, facial expression, and eye contact approach behaviors collected across multiple time points. Our findings suggested that social approach behaviors in children with FXS were affected by age, gender, setting, and time spent with an examiner. Selected social approach behaviors were related to autistic behavior. Increased eye contact over the course of a research assessment, in particular, was found to be a strong predictor of lower autistic behavior.