Background <p>Children in urban informal settlements are vulnerable to enteric pathogen exposures due to inadequate availability of clean water, sanitation, and wastewater treatment. These exposures can contribute to diarrhea, malabsorption, and poor growth. Understanding how children interact with their environments – particularly through mouthing behaviors – can help identify high-risk environmental sources, exposure pathways, and opportunities for intervention. The objective of the study is to characterize mouthing behaviors among young children and assess the environmental contexts in which these behaviors occur, in order to identify potential pathogen exposure risk.</p> Methods <p>Two videography campaigns were conducted involving 192 children under five years old (106 in Fiji and 86 in Indonesia), with a mean observation duration of 4.1&#xa0;h per child. Mouthing behaviors were recorded along with the environmental context (location and presence of risk factors (i.e., near human or animal feces, close to animals, or interacting with environmental water)).</p> Results <p>All children mouthed objects during observation. Mouthing frequencies were similar across countries: 68.6 contacts/h in Indonesia and 68.2 contacts/h in Fiji. Most frequently mouthed objects were food (25.5 in Indonesia, 16.9 in Fiji), fomites (17.4 and 24.4), and the child’s own hand (17.6 and 20.4 contacts/h). Outdoors, mouthing was common: 98% of Indonesian children and 91% of Fijian children, with frequencies of 58.9 and 50.1 contacts/h, respectively. Indonesian children spent significantly more time outdoors (26.3 vs. 8.2&#xa0;min/h; <i>p</i> &lt; 0.001). High-risk contexts were observed in 66% of children in Fiji and 93% in Indonesia, with over half mouthing objects while in these settings.</p> Conclusions <p>Systematically incorporating contextual information on the settings where mouthing occurs, enables a broader understanding of children’s potential pathogen exposure risks through child-environment interactions.</p>