Summary Permanency decisions in child welfare are recognised as being challenging. Nevertheless, society and the profession expect that professional judgements should be of the highest quality, consistent, reliable, fully justified and informed by evidence of what works, particularly where decisions are potentially life-changing. However, barriers to knowledge acquisition and utilisation exist, preventing practitioners from gaining the full range of knowledge they require, leading to permanency decisions being interventionist and protectionist in orientation (author, 2020). Think-aloud protocols and semi-structured interviews, in conjunction with a vignette, were used with social workers ( N = 17) in statutory services to explore barriers to knowledge acquisition and utilisation in permanency decisions for children in state care. Findings The main barriers to knowledge use were (1) misunderstanding or misuse of theory, (2) limitations in training and learning and (3) organisational issues. Applications By developing a real-world understanding of the barriers and listening to the views of the professionals themselves, we can begin to realistically inform policy and practice, with the aim of decreasing the barriers to knowledge acquisition and utilisation in permanency decision-making. If we appreciate the barriers to knowledge acquisition and utilisation in permanency decision-making more fully, then perhaps we can reduce them, thereby facilitating more fully informed decisions that best serve the individual needs of children and their families.