This thesis comprises a systematic literature review on research conducted on associations between attachment, behavioural difficulties and theory of mind in samples of children and young people. Research has demonstrated that a triangular relationship between social, emotional, and behavioural difficulties (SEBD), parenting/attachment and Theory of Mind (ToM) exists. Based on the results of the literature review, a pilot study was created to examine these three constructs in a different way. To date, no research has been found on the relationship between all three variables concentrating on children's distinct attachment style. The following pilot explored the relationship between pupils' attachment style, their competence in three different ToM tasks and their level of SEBD. All participants were males (N = 19) who attended primary-school Behaviour Support Units in Northern Ireland at the time of this study. Using a quantitative methodology, each variable was measured through one measurement (ToM = NEPSY II; attachment = MCAST; SEBD = SDQ), two of which were standardised. The data was analysed through effect sizes and descriptive statistics. Effect sizes measured through partial eta squared varied from small to large. Findings are not in line with past research and the replication of this study would be advised before drawing final conclusions from its results. In the third paper, a critical evaluation of the empirical paper, discusses the methodology and results of this research and provides a personal reflection on the process of writing this work.