offers an overview from the adult learning literature of adult motivations to learn, curriculum considerations when teaching adults, and classroom and teaching considerations.
This chapter by Raymond Wlodskowski describes a framework for motivating adult learners
A blog post with concrete suggestions and excellent resources for additional learning
Enhancing Adult Motivation to Learn by Raymond Wlodkowski, 2008
Learning in Adulthood: A Comprehensive Guide by Sharan Merriam and others, 2006
The Adult Learner, 7th Edition by Malcolm Knowles, 2011
Teaching Intensive and Accelerated Courses: Instruction that Motivates Learning by Raymond Wlodkowski & Margery Ginsberg, 2010