Background Trauma informed care (TIC) practices have been developed to diminish the range of negative consequences associated with adverse childhood experiences (e.g., unemployment, welfare, incarceration, and medical and psychiatric treatment). They have been demonstrated to benefit young people, their carers, and child welfare staff. However, a gap that has been identified in this area is the absence of psychometrically sound TIC instruments, which has hindered the TIC literature in terms of transitioning to a more methodologically robust and data driven research area.

Objective The current study aimed to develop a psychometrically sound instrument (i.e., the TIC Belief Scale) that could assess the TIC beliefs of child welfare carers who reside with youth.

Methods Initially, 143 items were developed based on widely used TIC models. After a review by an expert panel of 10 experienced trauma practitioners, 85 items were retained and administered to a sample of 469 child welfare carers. The psychometric properties of the scale were investigated using Item Response theory (Rasch analyses).

Results Following analyses, a final scale of 13 items was accepted. The scale had good internal reliability (PSI = 0.77), showed evidence of unidimensionality, and there was no evidence of differential performance across sub-groups.

Conclusions The application of the Rasch model in this study provides support for the TIC Belief Scale as a psychometrically sound scale for measuring child welfare carers’ beliefs about TIC practices. An algorithm proposed here for converting ordinal to interval scoring increases the precision in understanding carers’ less favourable TIC beliefs.