A general short form of the experiences in close relationships survey (Fraley RC, Waller NG, and Brennan KA, 2000). Details of the psychometric properties can be found in 'Wilkinson RB (in press) Meadering attachment dimensions in adolescents: Development and validation of the Experiences in Close Relationships - Revised - General Short Form. Journal of Relationships Research.'
Use average items to calculate scale score as per 'Wilkinson RB (2008). Development and properties of the Adolescent Friendship Attachment Scale. Journal of Youth and Adolescence, 37, 1270-1279.'