Children’s emotionality-fear, anger, and joy-observed outside of the relationship with the mother (in standard laboratory paradigms), and within that relationship (in mother-child interactions), and mothers’ responsiveness, all at 9 and 14 months, were examined as predictors of the reunion behaviors in the Strange Situation at 14 months in 112 children. Many predictors were linked to the reunion behaviors, but most of those relations were at least partially mediated by children’s separation distress, which itself strongly predicted the reunion behaviors. Those relations were no longer significant when distress was controlled. Several links, however, remained significant, and they were unmediated by distress: Almost all involved measures assessed within the context of the mother-child relationship. In particular, possible markers of a suboptimal relationship (children’s dampened joy and increased anger in interactions with the mother, poor maternal responsiveness) were associated with more avoidance and resistance upon reunion, even after accounting for the strong impact of distress. Studying how factors measured outside of and within early relationships influence the components of the attachment system may foster understanding of child behavior in the Strange Situation.