Reflecting on academic errors is a critical skill for engaging with feedback for learning. However, teachers lack training in knowing how to create environments that promote reflection and help students to acquire this skill (Metcalfe, "Annual Review of Psychology," 68, 465-489). Part of the problem is that many teacher education programs in North America and Europe do not require preservice teachers to explicitly reflect on their own academic errors. In fact, specific tools for probing, measuring and discussing preservice teachers' attitudes toward their academic errors are missing. In the absence of empirical evidence of preservice teachers' attitudes about errors, the effects of these attitudes on later practice remains unknown. The objective of the present study was to develop an inventory to measure preservice teachers' attitudes towards mistakes in learning environments. In two separate studies, the Attitudes Towards Mistakes Inventory--Learning Environments (ATMI-LE or ATMI for short) was developed and refined. The first exploratory factor analytic study involved 225 preservice teachers and was designed to develop the ATMI. The second confirmatory factor analytic study involved an independent sample of 207 preservice teachers and was designed to replicate findings from study 1 and refine the inventory. The second study incorporated other survey/scale measures to evaluate the criterion validity of the ATMI in relation to fear of failure, performance orientations, trust in instructor and persistence. Results indicated three distinct dimensions of the ATMI--beliefs, emotions and actions -- underlying preservice teachers' attitudes towards mistakes. Moreover, each dimension was internally consistent and shared expected correlations with related constructs.