DIDACTIC ENGINEERING AS DESIGN-BASED RESEARCH IN MATHEMATICS EDUCATION Juan D. Godino 1 , Carmen Batanero 1 , Ángel Contreras 2 , Antonio Estepa 2 , Eduardo Lacasta 3 and Miguel R. Wilhelmi 3 1 Universidad de Granada (Spain); 2 Universidad de Jaén (Spain) 3 Universidad Pública de Navarra (Spain) In this paper we analyze two approaches to research in mathematics education: "Design-based research" (DBR) and "Didactic engineering" (DE), in order to study their possible networking. The problem addressed in both approaches is the design and evaluation of educational interventions, providing research-based resources for improving the teaching and learning of mathematics. They also try to contrast existing theories, or characterize new educational phenomena. We conclude that DE could be seen as a particular case of DBR, linked to the "Theory of didactical situations", or that DBR is a generalization of DE that use other theoretical frameworks as foundations for designing teaching experiments. Key words: networking theories, didactic engineering, didactic design, teaching experiment, didactic resources. INTRODUCTION The view of Didactic of Mathematics as a "science of design" is highlighted by several authors (Wittman, 1995; Hjalmarson & Lesh, 2008a; Lesh & Sriraman, 2010). Lesh and Siraman consider mathematics education as a science oriented to design processes and resources to improve teaching and learning of mathematics and reflect on the purpose of research in mathematics education: “Should mathematics education researchers think of themselves as being applied educational psychologists, or applied cognitive psychologists, or applied social scientists? Should they think of themselves as being like scientists in physics or other “pure” sciences? Or, should t hey think of themselves as being more like engineers or other “design scientists” whose research draws on multiple practical and disciplinary perspectives — and whose work is driven by the need to solve real problems as much as by the need to advance relevant theories?” (Lesh & Sriraman, 2010, p. 124). Recent interest in Anglo-Saxon literature on design-based research (handbooks; special issues of high-impact journals) and on its role in mathematics education complements the traditional French literature on "Didactic engineering" (Artigue, 1989), which provided significant contributions from the 80's, but was virtually ignored in this literature. This suggests a certain isolation of the French didactic engineering regarding the research done in other countries with similar objectives.