We explored associations among the core behavioural features and developmental/cognitive abilities of 155 autistic children, assessed between ages 13-67 months and again around 1-year later to understand predictive directionality. Bidirectional, cross-domain association was apparent, albeit with stronger direction of effect from earlier cognition to later autism features (than vice versa). Exploratory sub-domain analysis showed that early non-verbal developmental/cognitive abilities (only) predicted subsequent "social"- and "restricted/repetitive" autism features, whereas early social features (only) predicted both subsequent "verbal" and "non-verbal" abilities. Although observational study design precludes causal inference, these data support contemporary notions of the developmental interconnectedness of core autism presentation and associated abilities--that behavioural autism features may influence cognitive development, but are likely also "influenced by" an individuals' cognitive capacity.