This mixed-methods dissertation examined the development of productive learning dispositions by studying children\u27s competence-beliefs about the self as a learner and producer of mathematics in a K-3 population in a Midwestern state. Support for this work comes in part from the National Science Foundation, DUE-0831835. Ideas expressed do not necessarily reflect the views of the funding agency. Three research questions were addressed through two phases of inquiry. Quantitative Phase: To what extent did K-3 students have stable math competence-beliefs? What was the underlying factor structure of these beliefs ( Math Confidence ) and was I measuring the same construct across grade levels? Qualitative Phase: What meaning did children ascribe to the symbols on the survey and how did these meaning systems change over the K-3 years (if at all)? A cumulative probit model for repeated measures demonstrated that competence-beliefs were more stable from fall to spring for second and third grade students. An Item Factor Analysis model demonstrated measurement non-invariance, indicating that K-3 students did not have the same expected pattern of item responses given the same level of Math Confidence. Three quantitative findings organized qualitative analysis: (a) the configural factor structure; (b) non-invariance; and (c) reliability procedures. Grounded theory techniques were applied to the interviews of 115 students across two districts. Six broad categories emerged: Performance Feedback; Motivation; Strategies for Promoting Competence; Mathematical Statements; Comparative Evaluation; and Behavior and Classroom Conduct. Thematic similarities and differences between grades varied by survey item. Quantitative results and qualitative findings were synthesized. Techniques for interviewing young children as well as implications for classroom practice were shared, followed by a discussion of the limitations of the study and future directions