Information Gathering is a knowledge construction process. Web learners make a plan for their Information Gathering task based on their prior knowledge. The plan is evolved with new information encountered and their mental model is constructed through continuously assimilating and accommodating new information gathered from different Web pages. In the process, learners have to maintain many search results for later use and coordinate information between different topics and different memory aids for understanding. However, currently widely-used Web browsers provide ineffective support for the process. Learners frequently encounter these problems, disorientation and cognitive load, and thus impede their learning. This study proposes an innovative Web browser interface called TopicBrowser, in which learners can make an Information Gathering plan with a hierarchical concept map. Based on the map, they can search information, group open Web pages into associated topics, extract information from within Web pages and organize it, and evaluate their Information Gathering process. An experiment with thirty participants was conducted to compare TopicBrowser interface with conventional tabbed browser interface. Experimental results show that TopicBrowser can lower the degree of disorientation, increase learners' retention, and increase the efficiency in completing an Information Gathering task. These results suggest that Web browser interfaces should provide effective ways of extracting and organizing search results. The well-organized information can significantly reduce disorientation and cognitive load and thus can improve learners' learning during Information Gathering processes. (Contains 3 tables and 2 figures.)