Psychometric properties of the French Infant-Toddler Working Alliance Inventory Short version (IT-WAI-S)

<b>Objective:</b> Therapeutic alliance has been little investigated in infant and toddler therapy, with no tools specifically adapted to this population. However, we have developed the Infant-Toddler Working Alliance Inventory-Short form (IT-WAI-S) which is based on the Working Alliance Inventory. The aim of this study was to assess the psychometric properties of this original French tool, in its two versions: for parent (IT-WAI-SP) and for therapist (IT-WAI-STh).<b>Method:</b> This study included 227 families consulting with their 18-48-month-old child for emotional or behavioral disorders. The scales were filled in at the first three therapy sessions. The IT-WAI-S acceptability, internal validity, reliability and predictive validity (association with child and mother's outcomes) were evaluated.<b>Results:</b> Confirmatory then exploratory factor analyses revealed a three-factor structure for the both scales: Negative Experience of Care Relationship, Positive Alliance and Alliance with the Child. Acceptability, reproducibility and construct validity were satisfactory for both versions. The two versions predicted the child's outcome. The IT-WAI-SP predicted also the mother's outcome. The IT-WAI-STh gave more reproducible results, whereas the IT-WAI-SP was a better predictor of the child's progress.<b>Conclusion:</b> The two IT-WAI-S versions showed good psychometric properties and could be used to study the therapeutic alliance in young children.