Nutrition is vital for optimal growth and development of young children. Nutrition risk screening can facilitate early intervention when followed by nutritional assessment and treatment. NutriSTEP (Nutrition Screening Tool for Every Preschooler) is a valid and reliable nutrition risk screening questionnaire for preschoolers (aged 3-5 years). A need was identified for a similar questionnaire for toddlers (aged 18-35 months). The purpose was to develop a reliable and valid Toddler NutriSTEP. Toddler NutriSTEP was developed in 4 phases. Content and face validity were determined with a literature review, parent focus groups (n = 6; 48 participants), and experts (n = 13) (phase A). A draft questionnaire was refined with key intercept interviews of 107 parents/caregivers (phase B). Test-retest reliability (phase C), based on intra-class correlations (ICC), Kappa (κ) statistics, and Wilcoxon tests was assessed with 133 parents/caregivers. Criterion validity (phase D) was assessed using Receiver Operating Characteristic (ROC) curves by comparing scores on the Toddler NutriSTEP to a comprehensive nutritional assessment of 200 toddlers with a registered dietitian (RD). The Toddler NutriSTEP was reliable between 2 administrations (ICC = 0.951, F = 20.53, p < 0.001); most questions had moderate (κ ≥ 0.6) or excellent (κ ≥ 0.8) agreement. Scores on the RD nutrition risk rating and the Toddler NutriSTEP were correlated (r = 0.67, p < 0.000). The area under the ROC curve for moderate and high RD risk ratings were 84.6% and 82.7%, respectively. Cut-points of ≥21 (sensitivity 86%; specificity 61%) (moderate risk) and ≥26 (sensitivity 95%; specificity 63%) (high risk) were determined. The Toddler NutriSTEP questionnaire is both reliable and valid for screening for nutritional risk in toddlers.