For the past 17 years, the U.S. National Commission on Mathematics Instruction (USNC/MI) has held workshops with mathematics educators from countries that typically perform well on international assessments and have a history of strong mathematics education programs, such as Japan, China, and South Korea. Finland is among this group. Even though its mathematics education system has some common characteristics with other top-performing nations, such as a great social respect for the teaching profession, it also has unique characteristics. The USNC/MI, a standing committee of the National Academies of Sciences, Engineering, and Medicine, planned a workshop at which U.S. and Finnish mathematics educators could exchange information and ideas about the preparation of new mathematics teachers and the means of providing them with support and professional development throughout their careers. While this is not the first time U.S. and Finnish mathematics educators have discussed educational practices, this workshop focused primarily on teacher development in both nations in the context of mathematics education. This publication summarizes the presentations and discussions from the workshop.