The experimental research is one of the most powerful approach in social science research, especially in the empirical examination of theories. The main purpose of this paper is to provide a comprehensive coverage for those interested in information systems research but unfamiliar with the experimentation approach. The thrust is to provide general guidance in its basic concepts and major validity considerations, and no attempt is made to provide a detailed guidance in conducting an experiment. This paper start out with basic philosophical foundations for empirical research, and introduces the major concepts such as theoretical construct, concepts and threats to validity, experimental design, operationalization, control and measurement of constructs, etc. Experimental researches in information systems, conducted in Taiwan and the U.S. are cited as examples in the process.