The purpose of this mixed-methods study is to examine the outcomes of assessment training for elementary teachers. Only 56% of the surveyed teachers (n = 283) had assessment training in their university courses, compared to 84% that received in-service training. The quantitative results indicate that frequency of assessment training is positively related to assessment self-efficacy, attitudes about assessment, and data-driven decision making practices. Within the qualitative data, teachers (n = 9) explained the conflicts within assessment training: idealism v. realism; pressure v. support; and technical competence v. transferrable understandings. This study demonstrates the importance of assessment training while providing several recommendations for enhancing the efficacy.