This special issue of the Canadian Mathematics Education Study Group/Groupe Canadien d'Étude en Didactique des Mathématiques (CMESG/GCEDM) Proceedings looks at CMESG/GCEDM's collective history, reflects on where the group has been, and who the members have become as an organization. Through a selection of excerpts from past proceedings, the editors have stitched together a partial history of CMESG/GCEDM's time as an organization. This serves not only as a summary of the collective history, but also serves as an introduction to the activities of CMESG/GCEDM through the first 40 years. The pieces selected for inclusion in this special issue stand as signposts along CMESG/GCEDM's history--as exemplifications of what CMESG/GCEDM is as an organization as well as the activities of CMESG/GCEDM at annual meetings. Crafted introductions to each piece articulate the ways in which that piece exemplifies the valued aspects of CMESG/GCEDM. Following an introduction to the special issue (Peter Liljedahl) [Written in English and French], a foreword (Peter Taylor) [Written in English and French], a Preface to the 1977 CMESG Proceedings (Albert Coleman, Bill Higginson, and David Wheeler), and The Origins and Activities of CMESG (David Wheeler), this issue contains the following papers: (1) Mathematics Education Research in Canada: A Prospective View (Tom Kieren); (2) Innovations in Teacher Education Programmes (Claude Gaulin); (3) The Objectives of Mathematics Education (Albert Coleman); (4) Confessions of an Accidental Theorist (Alan Schoenfeld); (5) The Role of Epistemology in the Analysis of Teaching/Learning Relationships In Mathematics Education (Michèle Artigue); (6) Alive Mathematical Reasoning (David Henderson); (7) Toward a Practice-Based Theory of Mathematical Knowledge for Teaching (Deborah Loewenberg Ball and Hyman Bass); (8) Mathematics as Medicine (Edward Doolittle); (9) Old and New Mathematical Ideas from Africa: Challenges for Reflection (Paulus Gerdes); (10) The Role of Proof in Post-Secondary Education (William Byers and Harvey Gerber); (11) From Theory To Observational Data (And Back Again) (Carolyn Kieran and Jo Towers); (12) Where Is The Mathematics? (John Mason and Eric Muller); (13) The Arithmetic/Algebra Interface: Implications For Primary And Secondary Mathematics = Articulation Arithmétique/Algèbre: implications pour l'enseignement des mathématiques au primaire et au secondaire (Nadine Bednarz and Lesley) [Written in English and French]; (14) Images Of Undergraduate Mathematics (Miroslav Lovric and David Poole); (15) A Mathematics Curriculum Manifesto (Walter Whiteley and Brent Davis); (16) Learner Generated Examples (Nathalie Sinclair, Anne Watson, and Rina Zazkis); (17) Étude des pratiques d'enseignement (Jamie Pyper, Hassane Squalli, and Laurent Theis) [Written in English and French]; (18) Mathematics of Planet Earth 2013: Education and Communication = Mathématiques de la planète terre 2013: formation et communication (Doug Franks, Kathleen Pineau, and Walter Whiteley); (19) Indigenous Ways of Knowing in Mathematics (Lisa Lunney Borden and Florence Glanfield); (20) The Commonsense of Teaching (David Wheeler); (21) A Historical Perspective on Mathematics Education Research in Canada: The Emergence of a Community (Carolyn Kieran); (22) Lessons from the Past, Questions for the Future: Méditation sur thème impose (Roberta Mura) [Written in French]; (23) Building Thinking Classrooms: Conditions for Problem Solving (Peter Liljedahl); (24) Where Do I Want Students' Attention? And What Can I Do to Affect Their Attention? (David Hewitt); and (25) Measuring the Impact of a Mentor Program (A. J. Dawson). Individual papers contain references.