Abstract:Algebra readiness has been characterized as the most important "gatekeeper” in mathematics. It is widely accepted that to achieve the goal of "algebra for all,” students in elementary school should have experiences that prepare them for more formal study of algebra in the later grades (e.g., NCTM, 2000). However, curriculum developers, educational researchers, and policy makers are just beginning to think about and explore the kinds of mathematical experiences elementary students need to prepare them for the formal study of algebra in the later grades (e.g., Carpenter, Franke, & Levi, 2003; Kaput, 1999; Kieran, 1996; Mathematical Sciences Education Board, 1998; NCTM, 2000; Schifter, 1999). This Special Issue of the journal provides an international perspective of developing students’ informal and formal algebraic thinking in elementary school. Case studies of the intended elementary mathematics curricula in China, Russia, South Korea, Singapore, and the United States are presented to show the ways different curricula provide students with informal and formal algebraic experiences. The findings from these case studies should help educators and curriculum developers establish a mechanism that provides students experiences with both algebraic ideas and thinking in the earlier grades. While any curriculum has a complex relationship with what actually occurs in classrooms, research has shown that curriculum substantially determines the course of instruction and learning in school (Schmidt, et al., 1996). Therefore, we believe that these case studies may also contribute to our understanding of the impact of curriculum and instruction on students' learning and understanding.