This study addressed the issue of school alienation (SA) among high school students in Taiwan; SA is believed to contribute to dropout, violence, gangs, and deviant behavior. To measure SA, we propose a four-construct model in this study, comprising powerlessness, normlessness, meaninglessness, and social isolation. Using two studies, an SA scale (SAS) was developed and validated. Study 1 developed and preliminarily validated the four constructs of SA using item and exploratory factor analyses with 227 junior high school students as participants. Study 2 validated the theoretical structure of SA using second-order confirmatory factor analysis with a sample of 708 junior high school students. The cross-validation of Studies 1 and 2 demonstrated that the proposed SAS is robust, valid, and effective for measuring the degree of SA among students.