Background: Ultra-processed food (UPF) consumption is increasing exponentially, becoming a matter of concern for Public Health, given its adverse health effects. Objective: To identify individual and faGmily factors predicting UPF consumption in childhood. Design: The SENDO project is an ongoing prospective dynamic cohort of Spanish children. In this study, we used baseline information of participants recruited between January 2015 and June 2021. Dietary information was collected with a validated semi-quantitative FFQ, and food items were classified using the NOVA classification. Individual and family factors associated with UPF consumption (P < 0 center dot 20) in univariate analyses were introduced in a model of generalised estimating equations which accounted for intra-cluster correlations between siblings. Setting: The SENDO project (Spain), 2015-2021. Participants: Spanish children are recruited at the age of 4-5 years and followed yearly through online questionnaires completed by parents. Results: In this sample of 806 participants (49 % girls; mean age 5 years (sd: 0 center dot 90)), the mean UPF consumption was 37 center dot 64 % of total energy intake (sd: 9 center dot 59). Large family size and longer exposure to screens predicted higher consumption of UPF. On the other hand, better knowledge of children's dietary recommendations, healthy dietary attitudes towards child's eating habits and longer breastfeeding were associated with lower consumption of UPF. All these factors accounted for approximately 16 % of the variability on the consumption of UPF in childhood. Conclusion: Since most of the factors identified in this study are modifiable, they should be considered in public health strategies aimed at promoting healthy dietary habits in early life.