Although the Web allows for flexible learning, research has found that online students tend to lack focus, willingness to participate, confidence, and discipline. This study thus attempts to promote Web-based self-regulated learning from the social cognitive perspective, which emphasizes the interactions among personal, behavioral, and environmental influences. This study has identified the most significant factors for personal, behavioral, and environmental influences in the social cognitive model of self-regulated learning, and also applied this model to the development of the NetPorts web-based learning system. NetPorts, in turn, allows us to empirically analyze the interactions between the aforementioned factors. Our Web-based findings support the social cognitive view of self-regulated learning: students who hold higher levels of motivation apply more effective strategies, and respond more appropriately to environmental demands, in the Web-based learning environment. These findings also further validate the application of the social cognitive model to Web-based learning through the NetPorts.