This article advocates for proactive, dynamic and comprehensive psycho-educational assessments for children and young people who have a history of complex trauma, because of its known effects on development and learning. A case study is shared of a young woman with a history of complex trauma because of exposure to parental neglect, multiple foster care placements, and abuse while in the care system. Background information on the impact of both early developmental trauma and interruptions to attachment with an early caregiver on learning and development is discussed, along with the benefits of using dynamic assessment. In particular, the case will expose how delays in thorough, high quality psycho-educational assessment not only impacts on educational outcomes, but also care outcomes. It also illustrates the importance of including measures of social emotional functioning as part of psychoeducational assessments when, as in this case, a review of developmental and learning needs is required in preparation for transition to high school, to assist funding applications for additional support, and to contribute to case planning towards reunification with siblings. Best practice protocols are shared that promote both multiprofessional and multi-dimensional assessment, including working between agencies, systems, group and individual assessment, and, most importantly, tools that facilitate both transformation of teaching practice and the voice of the young person; all serving to promote mental health and wellbeing.