Relationship dissolution can cause declines in emotional well-being, particularly if there are children involved. Individuals’ capacity to cope with the pragmatics of the situation, such as agreeing childcare arrangements, can be impaired. Before now, there has been no psychometric test to evaluate individuals’ emotional readiness to cope with these demands. This paper presents a model of emotional adaptation in the context of relationship dissolution and its key assumptions, and validates the Emotional Adaptation to Relationship Dissolution Assessment (EARDA). In Study 1 (Sample 1, n = 573 separated parents, Sample 2, n = 199 mix of parents and non-parents), factor analyses support the EARDA as a unidimensional scale with good reliability. In Study 2 (using Sample 1, and Sample 3, n = 156 separated parents) the convergent, discriminant, concurrent criterion-related, and incremental validity of the EARDA were supported by tests of association with stress, distress, attachment style, and co-parenting communication and conflict. In Study 3, the nomological network of emotional adaptation to relationship dissolution was explored in Sample 2 using cluster analysis and multi-dimensional scaling (MDS). Emotional adaptation clustered with positive traits and an outward focus, and was negatively associated with negative traits and an inward focus. Emotional adaptation was conceptually located in close proximity to active and adaptive coping, and furthest away from maladaptive coping. In Study 4 (n = 30 separated parents embarking on mediation), high, medium, and low emotional adaptation to relationship dissolution categories correlated highly with mediators’ professional judgement, offering triangulated face validity. Finally, in Study 5, EARDA scores were found to mediate between separation characteristics (time since break up, whether it was a shock, and who initiated the break up) and co-parenting conflict in Sample 1, supporting the proposed model. The theoretical innovation of this work is the introduction of a new construct that bridges the gap between relationship dissolution and co-parenting. Practical implications include the use of the measure proposed to triage levels of support in a family law setting.