Combining Bachman's (1990) conceptualization of content validity with Messick's (1989) unifying model of construct validity, this study attempted to fill the gap in researching content validation in the context of a university reading achievement test by (a) examining traditional content validity evidence and (b) analyzing the test scores to either back-up or rebut the evidence and explore the construct of the underlying test structure. On a sample of 477 third-year English-majored test takers at a Central Vietnamese University (CVU), the study was conducted in the pre-test stage where the test content was compared with the test specification and the post-test stage where the test scores were processed via Rasch and CFA competing model analyses. Results showed that while content relevance was satisfactory and the test construct was to a large extent not threatened by construct-irrelevant variance, content coverage of the test remained problematic with instances of construct underrepresentation. Moreover, the study supported the one-factor model of general reading ability as the underlying structure of the reading achievement test over the correlated three sub-skill and higher-order factor models. The study bears implications for both test writers in designing and test takers in performing the L2 reading test.