Background ALS clinical care and research has changed dramatically since the COVID-19 pandemic, accelerating the need for cognitive assessments to be adapted for remote use. Objectives To develop the remote administration method of the Edinburgh Cognitive and Behavioural ALS Screen (ECAS), and determine its reliability and validity. Methods: The validation process consisted of: (1) Two versions of the ECAS (A and B) were administered, one in-person and one remotely via video call in a randomized order to 27 people without ALS; (2) The ECAS was administered remotely to 24 pwALS, with a second rater independently scoring performance; and (3) Acceptability was assessed by gathering feedback from 17 pwALS and 19 clinicians and researchers about their experience of using the ECAS remotely. Results In the group without ALS, the remote and in-person ECAS total scores were found to be equivalent, and a Bland-Altman plot showed good agreement between the two administration methods. In pwALS, there was excellent agreement between two raters (ICC = 0.99). Positive feedback was gained from pwALS, researchers and clinicians with regards to ease of process, convenience, time, and the environment. Conclusions These findings provide evidence of the reliability and validity of the remote administration of the ECAS for pwALS, with clinicians, researchers and pwALS viewing it as a good alternative to face-to-face administration.