Inhibitory control (IC) is a core executive function integral to self‐regulation and cognitive control, yet is itself multi‐componential. Directed global inhibition entails stopping an action on demand. Competitive inhibition is engaged when an alternative response must also be produced. Related, but not an executive function, is temperamentally‐driven wariness of novelty, known as behavioural inhibition. Understanding early development of these components has been hampered by a shortage of suitable measures. We combine established and novel measures to capture directed global inhibition (Toy Prohibition, Touchscreen Prohibition), competitive inhibition (A‐not‐B, Early Childhood Inhibitory Touchscreen Task; ECITT) and behavioural inhibition (Touchscreen Approach) in 113 10‐ and 16‐month‐olds (73 seen longitudinally). ECITT performance shows good 1‐week test‐retest reliability at 10‐months (r = 0.30–0.60) but little stability to 16‐months. Directed global inhibition performance shows developmental progression but little stability of individual differences from 10 to 16 months. Performance on measures targeting similar IC components shows greater coherence at 16‐months (r = 0.23–0.59) compared with 10‐months (r = 0.09–0.35). Probing of ECITT condition effects indicates toddlers are more able, compared with infants, to override immediate prepotencies; indicative of increasingly flexible control over behaviour. However, exerting IC over cumulative prepotencies appears just as challenging for toddlers as infants. Exploratory analyses show little evidence for cross‐sectional or longitudinal associations between behavioural, directed global and competitive inhibition. In combination, these findings indicate that IC is not yet a stable, unidimensional construct during the transition between infancy and toddlerhood, and highlight the need for careful selection of multiple measures for those interested in capturing early variation in IC.

Inhibitory control (IC) is a core executive function integral to self-regulation and cognitive control, yet is itself multi-componential. Directed global inhibition entails stopping an action on demand. Competitive inhibition is engaged when an alternative response must also be produced. Related, but not an executive function, is temperamentally-driven wariness of novelty, known as behavioural inhibition. Understanding early development of these components has been hampered by a shortage of suitable measures. We combine established and novel measures to capture directed global inhibition (Toy Prohibition, Touchscreen Prohibition), competitive inhibition (A-not-B, Early Childhood Inhibitory Touchscreen Task; ECITT) and behavioural inhibition (Touchscreen Approach) in 113 10- and 16-month-olds (73 seen longitudinally). Pre-registered analysis of ECITT switching performance shows good 1-week test-retest reliability at 10 months (r=.60). Ten-month performance on directed global inhibition measures shows little stability to 16-months, and may be primarily influenced by behavioural inhibition. Performance on measures targeting similar IC components shows greater coherence at 16 months (r=.23-.59) compared with 10 months (r=.09-.35), and developmental progression across this period. Exploratory analyses (requiring replication) indicate possible reciprocal associations between behavioural and competitive inhibition across infancy into toddlerhood, yet limited cross-sectional associations. Probing of ECITT condition effects indicates that for 16-month-olds prepotencies may be more influenced by recency than repetition, whilst also interacting with side biases; important considerations when assessing early IC with tasks with a spatial component, as is common at this age. The study findings are informative for theoretical models and measurement of IC development across the transition between infancy and toddlerhood.