This first section of the Handbook is focused on the foundations that inform educational technology research and development. The purpose of this section is to provide a research-based overview of the foundations of educational technology pertinent to the twenty first century scholar- ship and practice. The intent is not to repeat anything explicitly covered in the three previous editions of the Handbook (Jonassen, 2004; Jonassen, Harris, & Driscoll, 2001; Spector, Merrill, van Merriënboer, & Driscoll, 2008), all of which are available online at no cost to mem- bers of the Association of Educational Communications and Technology (see http://www.aect.org) which sponsors the Handbook.