Statement of problem: In the evaluation of interdisciplinary interventions for childhood overweight and obesity, behavioural determinants can provide valuable insight into the reasons behind lack of adherence, or ineffectiveness of the intervention. Therefore, it is vital to assess the behavioural determinants of staff when evaluating the implementation of such interdisciplinary interventions. This study aimed to develop and psychometrically evaluate the intention to engage in Children's Healthy Weight guideline (iCHeW) scale, which assesses the behavioural determinants influencing dental staff's intention to conduct children's growth assessments. Methods: Initial items were generated based on review of the literature and the dimensions of the integrative model of behavioural prediction (IM). To test this scale, a cross-sectional survey design was undertaken consisting of three phases: (i) face validity; (ii) content validity; and (iii) psychometric evaluation of the iCHeW scale with a national sample of 125 dental staff. Results: The 35 items generated for the iCHeW scale were revised following feedback from a reference group. These 35 items were then appraised by an expert panel, yielding 27 items for psychometric testing. Using exploratory factor analysis, a five-factor solution was extracted, which corresponded to the IM domains, with the deletion of two items. Overall, Cronbach's alpha of the iCHeW scale was 0.95, with the following values for each subscale: (i) attitudes, 0.93; (ii) behavioural constraints, 0.83; (iii) perceived norms, 0.93; (iv) self-efficacy, 0.94; and (v) behavioural intention, 0.95. Conclusions: The iCHeW scale is valid and reliable for assessing dental staff's intention to provide routine growth assessments to children and demonstrates potential for use with non-dental staff.