The purpose of this study was to construct the Taiwan Adolescent Digital Reading Assessment (TADRA) and further to examine its validity. Researchers took the structure of the PISA 2009 electronic reading assessment (ERA) and Leu's (2004) online reading literacy as references to develop this tool which included three aspects: access and retrieve, integrate and interpret, and reflect and evaluate. Assessment material taken was from digital archive resources which possess high academic and educational value. The assessment system was developed on Internet/www platform, and runs and scors through ASP.NET. A pilot study was carried out in a junior high and high school in Taiwan. A total of 415 students, 216 8th graders and 199 10th graders, participated in the pilot study. Academic achievement of subjects was collected for preliminary testing TDARA's validity. After adapting classical testing theory (CTT) and item response theory (IRT), the results shown that P value is between 0.36-0.05, item difficulty parameter b is between 0.06-0.79, item discrimination is good (D=0.33-0.34); correlation coefficients between TADRA and Chinese is between 0.45-0.50, which is highest among all schools grades. This pattern demonstrates sensible supporting evidence for convergent and discriminant validity. Thease finding also indicate that basic searching ability is a requirement for online reading, hence differentiating online and offline reading.