This study investigates algebraic reasoning and self-regulation skills among elementary school teachers who participated in a professional development program either with IMPROVE metacognitive questioning (PD+Meta) or with no metacognitive guidance (PD). Sixty-four Israeli teachers participated in a 3-year program designed to enhance mathematical knowledge. Results indicated that the PD+Meta teachers outperformed the PD teachers on various algebraic procedural and real-life tasks regarding conceptual mathematical explanations. In addition, the PD+Meta group outperformed the PD group in using self-monitoring and evaluation strategies in algebraic problem solving. We discuss educational and practical implications.