The timeline for online Ph.D. programs is roughly the same as at a traditional university, four to six years, with a typical workload of 20 hours a week. Tuition averages $15,000 a year -- midway between most public and private university tuitions (but without the income that doctoral candidates count on as teaching assistants at bricks-and-mortar universities). Ph.D. studies fall into three categories of distance education.

Independent Study
Union Institute and University, based in Cincinnati, and Fielding Graduate Institute, in Santa Barbara, Calif., opened long before the online revolution and follow the tutorial model practiced at England's Oxford colleges. Students create their own multidisciplinary fields and choose their own reading and curriculum in consultation with advisers, who may well live in a student's community. Programs are only partly online, and group classes aren't a major component. Union (tui.edu) offers Ph.D.'s in interdisciplinary arts and sciences (among the concentrations: philanthropy, public policy, multicultural studies, social work, women's studies and peace studies). Fielding (www.fielding.edu) awards Ph.D.'s in psychology, human development, and human and organizational systems.

Online and Only Online
At the other end of the spectrum are the for-profits, including Walden and Capella Universities, both based in Minneapolis. (The University of Phoenix, the most well-known for-profit, offers only professional doctorates -- in business, pharmacology and other areas -- which do not require extensive original research.) Walden and Capella students attend one-week conferences in different locations several times a year. Walden (waldenu.edu) emphasizes what it calls social change. Capella (capella.edu) offers a more mainstream curriculum modeled after traditional universities. ''We are the most traditional of the nontraditional universities,'' says Karen Yasgoor, director of its industrial organizational psychology program. Both offer Ph.D.'s in education, psychology, health and human services and management, with varying concentrations.

Via Traditional Campuses
Some old-fashioned residential universities have begun virtual doctoral programs. One of the largest of these, Nova Southeastern University (www.nova. edu) in Fort Lauderdale, Fla., offers online Ph.D.'s in computer and information sciences. The University of Nebraska in Lincoln (www.unl. edu) has added online doctorates in education. Paradoxically, traditional campuses like Nebraska don't require online students to spend time on campus. Nebraska is also one of the few programs to use videoconferencing for oral exams, to facilitate the use of visual aids like charts.