The purpose of the paper is to provide a framework for integrating computer-adaptive tool in Word Picture Game (WPG), a program designed for studying Chinese words at elementary level. The paper aims at such areas as technology, theories and practice. All of the areas are being discussed within the category of L2 lexical learning in computer-adaptive learning environment. The reason to adopt computer-adaptive tool in WPG is based on the following premises: 1. Lexical learning is incremental in nature. 2. Learning can be measured precisely with tests (objectivist epistemology). In the course of WPG construction, I stress the design of a test theory, namely, a learning algorithm. The learning algorithm is designed under such principles that users experience both 'elaborative rehearsal’ (aspects in receptive and productive learning) and 'expanding rehearsal, (memory-based learning and repetitive act). These design principles are coupled with cognitive approaches for design and analysis of learning and instruction in lexical learning.