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 scholarship 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.