This study compared linear text-based and non-linear hypertext-based instruction in a handheld computer regarding effects on two different levels of knowledge (declarative and structural knowledge) and learner motivation. Forty four participants were randomly assigned to one of three experimental conditions: linear text, hierarchical hypertext, and star-shaped hypertext. Each participant studied an instructional material with exactly the same content across the conditions, but differently structured depending on the condition. The results show that linear text group outperformed star-shaped hypertext group in declarative knowledge construction. For structural knowledge construction and learner motivation, there are no significant mean differences among three conditions. It is implied that linear text can be more effective in declarative knowledge construction than non-linear hypertext in handheld-based learning environments. (Contains 1 figure and 1 table.)