The concept of human knowledge is a human construct, and therefore, researching experience from the point of view of those who are living it following a social constructivist paradigm will likely reveal valuable information. Topics covered in this review suggest that the topic "professional development of adult learners" might focus on (a) the choice of learning, in other words, why adults opt for open and distance learning, (b) professional development, (c) learning as adult learners, (d) professional practice, (e) quality assurance, (f) performance in distance education programs, and (g) challenges facing adult students. Approaches that deal with flexible learning are referred to as online or distance learning (ODL). Other examples of flexible learning options available to adult ODL learners are learning from work and employer engagement, part-time study, webbased or blended learning, time driven programs at students' pace, contact sessions, workshops and seminars.