How valid and reliable are mixed-mode approaches to data collection and what are the practical aspects of combining multiple methods? This study compared web-based assessment techniques with traditional paper-based methods of commonly used measures of alcohol use. Test-retest reliabilities were obtained, and tests of validity were conducted. A total of 255 participants were randomly assigned to 1 of 3 conditions: paper-based (P&P), web-based (Web), or web-based with interruption (Web-t). Follow-up assessments 1 week later Indicated reliabilities changing from .59 to .93 within all measures and across all assessment methods. Significantly high test-retest reliability coefficients support the use of these measures for research and clinical applications. No significant differences were found between assessment techniques, suggesting that web-based methods ore a suitable alternative to traditional methods. This cost-efficient alternative has the advantage of minimizing data collection and entry errors while increasing survey accessibility. The use of emergent web-based computer technology offers an unprecedented opportunity to conduct cross-sectional and longitudinal research studies in a cost-efficient manner while increasing survey accessibility to study participants and providing a more accurate data collection alternative to researchers. Implications for how to choose which method or methods to adopt be discussed in the context of sampling requirements, survey error, and costs.