Paola Sztajn is a Professor of Mathematics Education at North Carolina State University and is a Principal Investigator in Project AIM (All Included in Mathematics). Her research program focuses on elementary teachers’ professional development in mathematics and has been supported with several grants from different funding agencies. She has written over 90 papers, mostly focused on elementary school mathematics teachers and teaching. The overarching question guiding her over 20 years of work in mathematics education is: in which ways do practicing elementary teachers acquire and continue to develop the professional knowledge and identity needed to teach all students high quality mathematics?  She works with colleagues from different fields, in collaborative studies that allow for in-depth investigations of this complex question. Daniel Heck is Vice President of Horizon Research, Inc. in Chapel Hill, North Carolina and is a Principal Investigator in Project AIM. His research and development work spans many areas of mathematics education: classroom learning environments and discourse; teacher professional development design, enactment, and impacts; curriculum design and enactment; and student problem solving. Tying all of this work together is a central interest in how teaching and learning in school can tap into students’ intuitions, informal ideas, and insights to develop powerful, formal understandings of mathematics. He has enjoyed and benefitted from collaboration with colleagues in practice and research locally, across the country, and around the world who share this interest.  Kristen Malzahn is a Senior Researcher at Horizon Research, Inc. in Chapel Hill, NC and a co-Principal Investigator in Project AIM. She began her career as an elementary school teacher and went on to receive a M. Ed. in Curriculum and Instruction at the University of North Carolina at Greensboro. Over the past two decades, she has worked on several mathematics education research and evaluation projects and published a number of journal articles and book chapters, many of which focused on mathematics professional development for elementary and middle grades teachers. Understanding the successes and challenges of teaching, she is most interested in supporting teachers as they work to provide effective mathematics instruction for each and every student.