Parental alienation (PA) is a form of childhood emotional abuse in which one parent instrumentally uses the child to inflict psychological harm on the other parent for revenge. The consequences of parental alienating behaviours range from mild (e.g., the child shows a certain resistance towards visiting the targeted parent but warm parenting is still possible) to severe, where the positive affective parent–child bond is severed and extremely difficult to reinstate under family therapy. In PA processes, parenting is disrupted with the targeted parent and dysfunctional with the alienating parent. Consequently, the child is at a high risk of developing internalising (e.g., depression, anxiety) and externalising (e.g., use of drugs/alcohol, violence) problems during later developmental stages and through the lifespan. Although the prevalence and severity of PA cases in our societies are largely unknown, in part because the construct is still an ongoing debate among academics, practitioners and family justice professionals, different authors defend that it should be treated as a public health problem. Early prevention should be the primary objective and family justice, child protection and mental health services must coordinate efforts to support the families and promote the best conditions for the development of affected children.