Recent advances in the Web technology have been changing our life in various aspects. These advances have brought us new paradigms of education. The Web provides teachers with many opportunities to implement wide ranges of new teaching and learning practices, which supplement the traditional classroom teaching-learning. Especially, the Web enables so-called WBI (Web-based instruction) system as a teaching aid. Now the WBI system can incorporate multimedia information with various communication and collaborative tools. In order for the WBI system to be successful, various supports are necessary. One of such supports comes from assessment. In this work, an item pool system for leveled assessment is designed and implemented. The proposed system has the following characteristics. First, the item pool is classified into three categories subject, semester, and chapter. This categorization makes lookup easier and faster. Second, any teacher can use the item pool system and enter their questions into the item pool. Third, the proposed system reflects various levels of students for each course. Thus, students can select their exams based on their progress and background. Finally, it can make difficulty of each item to be objective by repeated tests and refinements.