Authentic materials are catching more attention in an age of internet-webbed world where information exchange is in rapid flow, which makes such materials more accessible and superior in numbers. The application of authentic materials in classroom settings becomes unavoidable. There already exists theoretical support of the facilitating effect of authentic materials in language learning (Berardo, 2006; Gardner, 2008; Guariento & Morley, 2001; Mishan, F, 2005; Nation, 2010; Nuttall, 1996; Wallace, 1992). However, practical evidence of using authentic materials in classroom settings remains scarce. To fill up the gap and further explore the effect of reading authentic materials on a) adult EFL learner’s vocabulary learning and retention and b) their perceptions in L2 reading, this current research proposes a themed authentic material reading approach. This current study applied a quantitative research method and was conducted in a large chain language center in Northern Taiwan. Three groups of adult EFL learners got involved, with one graded reader extensive reading group, another authentic material extensive reading group and the other intensive reading group. After a six-week treatment, two vocabulary tests were implemented followed by a questionnaire. The result showed that both experimental groups outperformed the control group in word learning and retention in general. It also revealed that despite a similar performance in both two vocabulary tests with the graded reader group, the authentic material group demonstrated a significantly more active attitude. This result echoes with previous extensive reading research (Horst, 2005; Gardner, 2008; Kweon & Kim, 2008; Pellicer-Sanchez & Schmitt, 2010) and further provides evidence on the facilitating effect of using authentic materials in vocabulary acquisition and learners’ learning attitudes.