The Maria Mitchell Observatory (MMO) is a Research Experience for Undergraduates (REU) site that has activities to introduce undergraduate students to high-level, professionally guided, research in astronomy and astrophysics. The Maria Mitchell Observatory is located in Nantucket, Massachusetts. The students will have the opportunity to acquire teaching experience by taking part in the MMO public outreach programs. The Nantucket Maria Mitchell Association has invited undergraduate students to conduct research at the MMO for 42 years. Each student and supervisor cooperatively plans the project, including the definition of the research topic and the writing of a scientific paper. The students have the opportunity to present their results at a local or national professional meeting. The results of the research are often submitted to refereed professional journals for publication. The directions of scientific research at the MMO include multi-wavelength studies of astronomical objects ranging from comets to stars, to circumstellar and interstellar matter, and to other galaxies. In addition to each student's individual project in one of these fields, the student participates in a common scientific project. The data for the research projects are obtained from various ground-based and space-based observatories. Students have access to the photographic plate collections of the MMO and the Harvard College Observatory to obtain historical data. The data from these photographic plate collections are used to reconstruct the long-term light curves of unusual variable stars. The research activities by the students involve state-of-the-art data reduction techniques and thoughtful physical interpretations. Students may also pursue studies in theoretical astrophysics.