Research has consistently demonstrated that for children and young people to be adaptive in this ever-increasingly complex world, they must be able to selectively attend and stay focused; reason and problem solve; exercise self-regulation to avoid being impulsive or reactive; take the perspective of others; mentally consider alternatives; reflect on the past or consider an imagined future; and flexibly adjust to change or new information. Furthermore, it is increasingly being recognised, in the fields of education and neuroscience, effective education does not just include a focus on academic teaching practices but also critical cognitive-emotional skill. These critical skills are referred to as executive functions (EFs) and are essential for goal-directed problem solving, flexible adaptation to changing circumstances, effective social functioning, and intentional learning. Recent years have witnessed a proliferation of interventions designed to enhance EFs across the schooling years. One approach that has received increased attention and growing evidence is mindfulness-based intervention (MBIs) with potential benefits on socialemotional, executive and behavioural functioning in children and young people. In light of the encouraging findings in the extant literature, the aim of Study 1 was to examine the effects of a novel daily, routine MBI, embedded within the existing curriculum to improve executive functioning and behaviour in young children. A waitlist control design was employed where a sample of 91 early years school children in Preparatory Year, Grade 1 and Grade 2 were randomly assigned to either the MBI or a business-as-usual (BAU) control condition that delivered the Australian Curriculum. Participants assigned to the intervention group received the MBI across two school Terms whereas the control group received BAU followed by the MBI in the second Term. At three time points, participants completed two behavioural measures of EFs and teachers completed the Strengths and Difficulties (SDQ) – Teacher Report Questionnaire to assess student behaviour. Results showed that (i) that relative to children in a waitlist control condition, those children who participated in the MBI, showed improvements in cognitive flexibility, (ii) significant gains in measures of behaviour, most notably in attention and concentration were found, (iii) teachers were able to successfully embed the MBI within the normal school curriculum and (iv) waitlist control students improved favourably once they received the MBI. Study 2 was a replication of Study 1 with a larger cohort of participants. A cluster waitlist control design randomised seven classrooms with a total of 137 students to receive either the MBI or business-as-usual Australian Curriculum. Participants completed the same measures of EFs with teachers completing the SDQ at three timepoints. In line with findings from the original study, children who received the CalmSpace program compared to BAU demonstrated improvements on the DCCS, Total SDQ score, and the Hyperactivity/Inattention subscale of the SDQ. Results of the replication study provide additional evidence that a brief, daily, repeated MBI embedded within the school curriculum can impact early years students EFs and behaviour. Study 3 extends the previous findings by further investigating the association between MBIs and EFs and behaviour from the combined data obtained in Study 1 and 2 (N = 223). Two simple mediation models, in which the association between an MBI and change in behaviour outcomes was proposed to be influenced by changes in EFs, namely inhibitory control and cognitive flexibility. Both models were tested in the PROCESS mediation analysis, with the cognitive flexibility model providing partial mediation. Overall, the current thesis advances the literature on the impact of MBIs in a school setting in several important ways. Firstly, the thesis demonstrates that a daily, routine MBIs that employs brief mindfulness-based activities can be embedded within the school curriculum and impact the development of EFs and student behaviours, notably attention and concentration, which have implications for school success and life outcomes (Study 1 and 2). Study 3 extended the findings of Study 1 and 2, investigating the potential underlying mechanisms or causal pathways that may be implicated in the delivery of MBIs and its effects on student attention and concentration. These findings have important implications for future research, policy design, and practice.