"Out-of-field teaching" is an international phenomenon that seems particularly prevalent in mathematics. Our study is evaluating the impact of a national professional learning program for out-of-field secondary mathematics teachers in Ireland. Using the Productive Pedagogies framework, we compared the pedagogical practices of three pairs of teachers who were either upskilled, still out-of-field, or always in-field. The findings suggest that graduates of the upskilling program are developing pedagogical practices more like those of in-field teachers.