--- - |2+ Background This study addresses the need for a theoretical base to develop more effective early autism spectrum disorders (ASD) detection tools. The structure that underlies early ASD detection is explored by evaluating the opinions of experts on ASD screening tools currently used in Europe. Method A process of face and content validity was performed. First, the best constructs were selected from the relevant tests: Checklist for Early Signs of Developmental Disorders (CESDD), Checklist for Autism in Toddlers (CHAT), Early Screening of Autistic Traits Questionnaire (ESAT), Modified Checklist for Autism in Toddlers (M‐CHAT), Social Communication Questionnaire (SCQ) and Communication and Symbolic Behaviour Scales Developmental Profile (CSBS‐DP). The diagnostic content validity model by Fehring (1986, 1994) was adapted to make the selection. Afterwards, the items, taken from these tests, were selected to fit into each construct, using the same methodology. Results Twelve of the 18 constructs were selected by the experts and 11 items were chosen from a total of 130, reduced to eight after eliminating tautologies. Conclusions Mapping these constructs and items on to the DSM‐5 diagnostic criteria for ASD indicated good face and content validity. Results of this research will contribute to efforts to improve early ASD screening instruments and identify the key behaviours that experts in ASD see as the most relevant for early detection. - Child and Adolescent Mental Health, Volume 23, Issue 4, Page 359-367, November 2018.