The 5th edition of the prestigious AECT Handbook continues previous efforts to reach outside the traditional instructional design and technology community to the learning sciences and computer information systems communities toward developing a conceptualization of the field. However, given the pervasive and increasingly complex role technology now plays in education since the 1st edition of the Handbook in 1996, the editors have reorganized the research chapters in this edition to focus on the learning problems we are trying to solve with educational technologies, rather than to focus on the things we are using to solve those problems. Additionally, for the first time this edition of the Handbook reflects our field's growing understanding of the importance of design scholarship to inform practice by including design case chapters.  These changes for this edition of the Handbook are intended to bring educational technology research into the broader framework of educational research by elaborating on the role instructional design and technology plays as a scholarly discipline in addressing education's increasingly complex issues.