The advance of computer and network technology has made it possible for students to flexibly acquire real-time information through distance education, allowing life-long learning. As in previous studies, the researchers found that students generally experienced less instructional interaction in distance education as compared to the traditional classroom setting. The purpose of this study was to develop and test a reliable and valid instrument to evaluate instructional interactions in synchronous distance education. Based on a literature review and researcher experience, a 36-item interaction scale was developed and administered to 100 students from two different schools. Data were collected and the reliability and validity of the scale were tested. The results showed that the scale had a Cronbach's alpha coefficient of 0.901. Factor analysis was used to test the construct validity and 29 items were extracted and divided into seven different interaction factors. These seven factors explained 72.69 % of the total variance. Furthermore, the results showed that the scale had good internal consistency and construct validity, and would therefore provide an effective and useful tool for evaluating interaction in synchronous distance education. Use of this instrument can help teachers to understand interactions taking place in a synchronous distance education environment and provide guidance for the future development of distance education programs for various disciplines.