Using Information Diagnosticity constructs to augment the e-commerce technology acceptance model (eTAM), the research model in this study extends the predictive accuracy of online purchase behavior by accounting for influences derived from electronic word-of-mouth (eWOM). Additional insights into buyer decision making through online sales vendors, such as Amazon.com, were assessed. The data analysis conducted using SmartPLS of 218 online shoppers indicates that the new eTAM assesses trusting tendencies influences on purchase behavior. This research indicates a shift in technology acceptance behavior antecedents from usefulness to trust. In an age where online personal information and financial data breaches are in the news often, trust in the ecommerce process is a significant aspect of online commerce adoption and purchase intentions. The extension of eTAM via information diagnosticity strengthens predictive aspects of the model in the ecommerce environment.