Researchers have noted that restorative justice (RJ) practices in schools seem to improve targeted outcomes (e.g., decreased office visits, increased grades, etc.). It has been acknowledged that a 'grass roots' (beliefs level) buy-in from teachers is necessary for the creation of a school environment that is in line with the ideals of RJ. In the current study, an operational definition for restorative justice ideology was developed and used as the basis for the creation of a Restorative Justice Ideology (RJI) measurement instrument. This is intended to facilitate understandings of the influence that RJ training has on individuals at the beliefs level, and whether the degree to which an individual holds an RJI is associated with the degree to which RJ practices are carried out at the classroom and school level. An exploratory factor analysis was conducted, a three-factor model was selected, and the instrument was tested for reliability and validity. The RJI was then used to investigate whether other individual differences were related to the RJI of teachers. The outcome of this study was the development of a psychometrically sound RJI instrument. Perspective-taking, empathic concern, pupil control ideology, personal distress, and self-efficacy were identified as important characteristics of RJI.