Modern astronomy has developed rapidly in the last few decades. Large telescopes, several metres in diameter, have been constructed and installed at many sites around the world, in order to carry out high-quality research work at the frontiers of astronomy. In many parts of the world, only small telescopes are available, because of budgetary limitations and the stage of development of science in the country. However, much effort has been put into using these small telescopes to the best of their capabilities. A small telescope with modern detectors can do good astronomical research. Sirindhorn Observatory, Chiang Mai University, is the only observatory in northern Thailand which plays an active role in astronomical research. The major instrument is the 40-cm Cassegrain reflecting telescope with standard wide-band and intermediate band photoelectric photometers, CCD photometers and a CCD spectrograph. Because of Thailand’s hot and humid climate, the telescopes and detectors at Sirindhorn Observatory need regular maintenance. Major research at the Observatory emphasizes the study of physical propoerties and evolution of close binary systems, especially near-contact and contact binaries, by photometric techniques. Networks in this field of research have been established through national and international collaboration with some astronomical institutes in the region. A larger telescope is being developed for more efficiency in operation; it is expected to be able to serve the future development of astronomical research in Thailand.