Family mealtimes are associated with benefits for children, including healthy eating, fewer behavior problems, and healthy psychological well-being. However, the interactions during family mealtimes, and the parent and child characteristics, which may affect both the family mealtime environment and the associated benefits in children are not fully understood. The goal of this study was to examine the role of child and parent characteristics on the family mealtime environment. We tested several mediation models to explain how child temperament (negative affectivity), parent stress, and the dimensions of parent feeding style (responsiveness and demandingness) interact and influence each other to impact the structure and quality of the mealtime environment. Parents (68 mothers; 82 fathers) of children between 2 and 6 years completed an online survey. Measures included the Children's Behavior Questionnaire, Perceived Stress Scale, Caregiver's Feeding Styles Questionnaire, and The Meals in Our Household Questionnaire. Child negative affectivity was associated with poorer mealtime quality and structure. These associations were mediated through parent responsiveness, but not demandingness. The role of demandingness in family mealtimes may depend on parent responsiveness. When examined together in a serial mediation model, child negative affectivity increased parent stress, which reduced responsiveness, and led to poorer mealtime quality and structure. These results emphasize the complex relationships between child temperament, parent stress, and the dimensions of parenting styles that occur within the mealtime context. This line of research is essential for understanding family mealtime dynamics and informing future studies aimed at creating positive interactions between parents and children during mealtimes.