In 1997 the British Columbia Open University (BCOU) adopted a virtualization strategy based primarily on twinning off-line independent study distance education courses (textbook-based with study guide and telephone and e-mail tutor support) with alternate online versions (textbook-based with integrated conferencing and communications provided through a learning management system). The intent was two-fold: (a) To increase course completion rates to British Columbia (BC) system levels, and (b) To establish a strong online presence, rapidly and cost effectively. "Course-twinning" also provided an opportunity to assess the impact of online delivery on independent study course completion rates. In this study we benchmarked successful completion rates (SCRBs) for BCOU's online academic courses and compared those to off-line course benchmarks. Online SCRBss are consistently higher than off-line SCRBs. Online SCRBs gains follow a clear pattern: they increase with course level and subject matter classifications and are particularly large at the upper-level and in more quantitative disciplines (up to 21.2% increase). Online successful completion rates are comparable to BC system performance statistics in the credit course areas but fall well short for Adult Basic Education (ABE) courses. Since evidence from a contemporary course survey indicate that BCOU student participation in online course versions is not linked to demographic characteristics associated with successful completion rates, we suggest that BCOU student success online results primarily from benefits of online course delivery. We discuss the implications of these results. (Contains 10 tables.)