Most scientists and engineers find careers in three general sectors of society: colleges and universities, industries, and federal and state agencies. Their work includes an array of activities, from the conduct of basic and applied research to the design and application of new commercial products to the operation and maintenance of large engineering systems.

Many science-related careers do not require a PhD. In such fields as biotechnology, hydrogeology, environmental engineering, science and technology policy analysis, and science journalism, for example, the bachelor's or master's degree can lead directly to a productive career. It is common for engineers to terminate their studies at the bachelor's or master's level; some engineers add a master's degree after beginning employment. A doctorate is appropriate for most students who desire research careers, including academic research and industrial research. But a doctorate does not restrict a person to a life at the bench or in academe. For example, of senior scientists and engineers employed in business or industry, one-third work in management.

In contrast to undergraduate study, which introduces you to a wide range of subjects, even though you major in one, a graduate program involves specialized knowledge and concentrated study in one area. There are professional and research degrees at both the master's and doctoral levels:

	The Professional Master's gives you a specific set of skills needed to practice in a particular field, such as education, business, engineering or other profession requiring specialized training. It is generally a final or "terminal" degree, and often involves an internship, practicum or field work. There may be a comprehensive exam at the end of the program.
	The Research Master's provides experience in research and scholarship, and it may be a final degree or a step toward the Ph.D. A master's degree usually takes one or two years of study. The student usually defends a thesis in order to obtain the degree.
	The Professional Doctorate. The M.D. for medical practice or the J.D. for law are the most common professional degrees.
	The Research Doctorate. The Ph.D. (Doctor of Philosophy), is the primary credential for college level teaching. The Ph.D. typically involves both course work and a major research project. The Ph.D. usually takes a minimum of four to six years of full-time study. The Ph.D. program usually includes passing a comprehensive exam for entrance to candidacy for the degree, and then a formal defense of the thesis. In place of a thesis, the Ph.D. student may be required to write and submit three journal articles approved by his or her committee.

If you decide to pursue graduate education specifically to advance your career, you may only need the two-year investment in a master's. However, some schools do not allow you to apply for only a master's degree; you must apply to a Ph.D. program and get your master's along the way. Keep in mind that if you choose to complete the M.S. degree and later decide to go on for a Ph.D. at another institution, the doctoral program may accept only a few transfer credits and require you to repeat the master's program.