The design, usage, and evaluation of a Web-based laboratory manual (WebLM) are described. The main aim of the WebLM is to support students while working in the laboratory by providing them with just-in-time information. Design guidelines for this electronic manual were derived from literature on cognitive load and user interface design. The WebLM was introduced in a Food Chemistry course at the Wageningen University. The evaluation showed a positive attitude towards the WebLM both by students (n = 79) and supervisors (n = 6). Furthermore, the WebLM proved to be a flexible platform, easy to maintain by teachers, easy to extend for future projects, and a promising research tool for monitoring student behavior in the laboratory classes. (Contains 4 tables and 5 figures.)