Background Stunted growth and development is a serious global public health problem. A limited number of field measures exist that can be used to evaluate stunting and its underlying biologic mechanisms. Purpose To assess bone age using tablet-based US in young children living in a rural community in Ecuador, where stunting is prevalent, and to evaluate the associations between bone age, anthropometry, and diet. Materials and Methods From June through August 2017, tablet-based US was used to assess bone age in young children within their homes in rural Cotopaxi, Ecuador. Bone age z scores (BAZs) were assigned using the standards of Greulich and Pyle. Anthropometric data were collected using international protocols; z scores were generated from World Health Organization Child Growth Standards. Groups were compared using the Student t test. Univariate analyses and generalized linear regression modeling were applied to test the association between bone age and anthropometry, adjusting for covariates including age, sex, dietary intake, and morbidities. Results A total of 128 children (mean age, 33.9 months ± 1.8 [standard deviation]; 59 girls, 69 boys) were evaluated. Mean BAZ was -1.20 ± 1.16. Mean BAZ was lower in children with stunted growth (-1.42 ± 1.18) than in children without stunted growth (-0.98 ± 1.10, P = .04). In adjusted analysis, BAZ was associated with the following variables: height-for-age z score (β coefficient, 0.26; 95% confidence interval [CI]: 0.05, 0.46; P = .01), female sex (β coefficient, 0.51; 95% CI: 0.15, 0.88; P = .006), number of times eggs were consumed in the previous 24 hours (β coefficient, 0.22; 95% CI: 0.05, 0.38; P = .009), number of times savory or salty snacks were consumed in the previous 24 hours (β coefficient, 0.42; 95% CI: 0.15, 0.68; P = .002), and ownership of pig livestock, which was a binary variable (β coefficient, -0.46; 95% CI: -0.82, -0.09; P = .01). Conclusion Bone age determined using tablet-based US was lower in children who had stunted growth and was associated with diet in a cohort of children living in rural Ecuador. © RSNA, 2020 See also the editorial by Dillman and Ayyala in this issue.