The development of forensic evaluation scales is fundamental. This study’s purpose was to explore the psychometric properties of a parental alienation scale. Forensic technicians completed 193 scales concerning parents involved in a lawsuit: 48 families with at least one parent indicated as the alienator (group A) and 48 families with no parental alienation claim (group B). The scale consisted of five categories and 69 items: denying access to the child; derogatory comparisons; emotional manipulation; behavior of parent and child during assessment. The results show Cronbach’s alpha = .965 and split-half = .745; KMO = .884 and Bartlett’s sphericity test ( p < .001). Concurrent criterion validity applied to data showed that the scale is able to distinguish between the alienator and target parent. The results showed significant and consistent standards in the instrument’s psychometric characteristics.