The purpose of educational research is to develop the state of learning and teaching by gathering data about the causes of the problematic issues and the way of coping with them. To achieve this goal, educational researchers should follow a specific methodology that enables them to obtain valid and reliable research results. The present article attempts to supply information about the principles of research methodology in education. First, it portrays the historical background of educational research. Then, it explains the basic philosophy of research adopted within the domain of social sciences in general and education in particular. After that, it lists the research methods applied in educational research and describes the principal steps and procedures embodied in the design of a research work. Thus, it gives an overview of the types of variables, information sources and the sampling methods involved in educational research. Furthermore, it enumerates the different research instruments employed for data collection. Also, it elicits the various types and forms of data analysis. Finally, the article presents an account of some limitations of the methodology of educational research and provides a set of suggestions that may help the researchers to decrease bias and get reliable findings.