This intervention case study is written by an Educational and Child Psychologist in the Republic of Ireland, which took place with Leah, a 15-year-old adolescent with a diagnosis of autism attending a post-primary school. Pre- and post-intervention assessment measures included the Strengths and Difficulties Questionnaire (SDQ) and the Rosenberg Self-Esteem Scale (RSE). An individualised intervention plan was designed, focussing on promoting Leah's self-esteem, as well as her understanding of autism. Therapeutic techniques used throughout the six-session intervention involved strengths-based and Personal Construct Psychology (PCP) approaches, alongside psychoeducation about autism. Leah's post-intervention scores on the SDQ showed slight improvements in emotional problems and conduct problems following the intervention, while her scores on the RSE demonstrated a significant improvement in self-esteem from pre- to post-intervention. The case outcomes support the adoption of individualised strengths-based approaches and PCP techniques to promote self-esteem, as well as psychoeducation about autism to promote understanding and self-acceptance.