**Introduction and Purpose:** Vaccine hesitancy represents a significant hazard to public health and well-being, with recent outbreaks of vaccine-preventable diseases being attributable to geographical pockets of hesitancy. Efforts to assess the scale of this problem and to evaluate our interventions are predicated on efficient, effective and standardised measurement. To date, no standard measure has emerged, with a preponderance of ad hoc scales and limited assessment of measure characteristics. This study will utilise item response theory to develop and provide initial validation of a measure of vaccine hesitancy that will be suitable for use in large scale, phone assessments.
**Method:** To investigate this, online data was collected from a sample of USA residents via MTurk (n = 206). Participants' level of education, mistrust of science, and other constructs previously linked to vaccine hesitancy were also assessed to provide evidence of convergent validity.
**Results:** A 2-parameter item response theory model was applied to assess the difficulty and discrimination of items assessing vaccine hesitancy. A candidate scale of 13 items was drawn, with difficulties ranging from 0.097 to 1.904, this scale significantly correlated with Mistrust in Science (r =.538), Authoritarianism (r = .364), Social Dominance orientation (r = .554), and Conspiracy beliefs (r = .344).
**Conclusions:** The new measure provides opportunities for more widespread assessment of vaccine hesitancy, and efficient assessment of the impacts of interventions both in primary healthcare settings and in community research.
**Corresponding author:** Mathew Ling (m.ling@deakin.edu.au<mailto:m.ling@deakin.edu.au>)
