The importance of interactions between child temperament and parenting has been accepted ever since Thomas and Chess (1977) proposed their “goodness-of-fit” construct, but over the last three decades, pertinent research has grown exponentially. Researchers examining child characteristics that can moderate the effects of socialization have tested increasingly complex, nuanced, and sophisticated models, largely inspired by the highly influential frameworks of child plasticity or differential susceptibility (Belsky & Pluess, 2009). Yet, multiple questions remain unsettled. We addressed four such questions as applied to predicting children’s observed disregard for rules at age 4.5 in a study of 200 community families from the US Midwest. (a) We examined children’s observed negative emotionality at 16 months, most commonly seen as a plasticity “trait,” but separating anger and fear proneness, which may differently moderate effects of socialization. (b) We examined two separate aspects of observed parental socialization at age 3, mutually responsive orientation and power assertion. (c) We distinguished analytically diathesis-stress from differential susceptibility. (d) We examined all effects in mother– and father–child relationships. We supported both diathesis-stress and differential susceptibility, depending on the facet of negative emotionality, the aspect of socialization considered, and parental gender, highlighting the nuanced nature of the processes involved.