Objectives: PEAK Relational Training system is a comprehensive curriculum programme for children with autism that combines traditional Applied Behaviour Analysis (ABA) techniques with innovative research on stimulus equivalence and derived relational responding. The current research investigated the impact of the PEAK Relational Training Systems, specifically the Equivalence (PEAK-E) and Transformation (PEAK-T) Modules, on cognitive and language abilities of typically developing preschool children. Methods: Thirty-nine typically developing children from a preschool (age 3-4) were recruited for Study 1. Participants were randomised into either PEAK-E intervention (n=13) or PEAK-T intervention (n=13) or treatment as usual (TAU; n=13) groups. Outcome measures included The Peabody Picture Vocabulary Test, Fourth Edition (PPVT-4); The Theory of Mind Inventory (ToMI); and the Bracken School Readiness Assessment, Third Edition (BSRA-3). Results showed a statistically significant increase in pre-post intervention ToMI scores for the PEAK-E and PEAK-T groups, but not for the TAU group. Post-intervention BSRA-3 scores were significantly higher for the PEAK-E group than for PEAK-T and TAU groups. Survey data from n=2 teachers suggest that the PEAK curriculum is socially valid. Study 2 was designed to determine the intervention-stage at which the PEAK-E module impacted BSRA-3 scores; specifically, would halting the intervention mid-stage suffice to improve school readiness. Thirty-six typically developing children from a preschool (age 3-4) were randomised into either PEAK-E intervention (n=18) or TAU (n=18). Outcomes on the BSRA-3 were measured at baseline, mid-intervention and post-intervention. Generalisation probes were also taken to determine whether intervention effects generalised to novel classroom materials. Results showed a statistically significant difference between PEAK-E and control on BSRA-3 scores. Within group analysis indicated a statistically significant increase from baseline to mid-stage BSRA-3 scores for the PEAK-E treatment group. Generalisation scores for the PEAK-E group were significantly higher than TAU. Conclusions: The results suggest that PEAK-E may have utility in affecting school readiness scores; however further research is required.