Dissertations often contain cutting-edge research and fresh perspectives. However, they are generally not peer-reviewed, and some professors will indicate that dissertations are not acceptable sources for an assignment. Even if this is the case, dissertations may be useful as a way to find peer-reviewed research as they have extensive literature reviews and bibliographies.
Dissertations are requisites for finishing PhDs. Consequently, they are written by budding academics and professionals. Dissertations contribute new knowledge to an academic field, and sometimes contain groundbreaking information yet to be acknowledged by the academic community. They are typically book-like in length. Dissertations are defended to a committee, but not always peer-reviewed like journal articles. Resultantly, they may not be completely reliable resources. If you're unclear on whether dissertations would be an appropriate source to use for your research project, ask your professor. For more information, consult the leftmost box.
