Identifying toddlers at dietary risk is crucial for determining who requires intervention to improve dietary patterns and reduce health consequences. The objectives of the present study were to develop a simple tool that assesses toddlers' dietary risk and investigate its reliability and validity. The nineteen-item Toddler Dietary Questionnaire (TDQ) is informed by dietary patterns observed in Australian children aged 14 (n 552) and 24 (n 493) months and the Australian dietary guidelines. It assesses the intake of ‘core’ food groups (e.g. fruit, vegetables and dairy products) and ‘non-core’ food groups (e.g. high-fat, high-sugar and/or high-salt foods and sweetened beverages) over the previous 7 d, which is then scored against a dietary risk criterion (0–100; higher score = higher risk). Parents of toddlers aged 12–36 months (Socio-Economic Index for Areas decile range 5–9) were asked to complete the TDQ for their child (n 111) on two occasions, 3·2 (sd 1·8) weeks apart, to assess test–retest reliability. They were also asked to complete a validated FFQ from which the risk score was calculated and compared with the TDQ-derived risk score (relative validity). Mean scores were highly correlated and not significantly different for reliability (intra-class correlation = 0·90, TDQ1 30·2 (sd 8·6) v. TDQ2 30·9 (sd 8·9); P= 0·14) and validity (r 0·83, average TDQ ((TDQ1+TDQ2)/2) 30·5 (sd 8·4) v. FFQ 31·4 (sd 8·1); P= 0·05). All the participants were classified into the same (reliability 75 %; validity 79 %) or adjacent (reliability 25 %; validity 21 %) risk category (low (0–24), moderate (25–49), high (50–74) and very high (75–100)). Overall, the TDQ is a valid and reliable screening tool for identifying at-risk toddlers in relatively advantaged samples.