Background: The area of child custody assessments continues to fail to meet the evidence-based threshold now established in clinical practice. This is despite the existence, for many years, of published guidelines governing the practice of custody assessments available from a number of professional bodies. Methods: This article reviews the potential of attachment theory to contribute to the conceptualization of custody evaluations, clinical assessment, and the development of evidence-based practice. Particular attention is paid to specific instruments used to assess attachment in clinic and non-clinic settings. Results: Guidelines concerning child custody assessments highlight the particular importance of assessing attachment and parent-child relationship quality. However, measures often used in the course of a custody assessment are not backed up with empirical research, and the measures that are supported by empirical research have been slow to influence practice. There may be conceptual and measurement advantages of considering an attachment research-informed custody assessment. Discussion: Attachment theory has obvious conceptual relevance for the child custody context. Further clinical research is needed to demonstrate the usefulness of attachment research measures; research of this kind may shed important light on the development and resilience of affectional bonds.