Research on animated pedagogical agents (agents) is viewed as a very positive attempt to introduce more pedagogical support and motivational elements into multi-media instruction. Yet, existing empirical studies that examine the learning benefits of agents have had very mixed results, largely due to the way that they are designed. This article will suggest five design principles for future research on the impact of agents on learning and motivation including: 1) The Balanced Separation Principle describes need for adequate controls that tease out the specific type of learning and/or motivational support the agent is providing; 2) The Variety of Outcomes Principle suggests different measures to test a variety of learning and motivation outcomes that may be influenced by agents; 3) The Robust Measurement Principle advises researchers to pay special attention to the reliability and construct validity of experimenter designed measures; 4) The Cost-Effectiveness Principle recommends the collection of data on the relative cost of producing agent and non-agent treatments; and 5) The Cognitive Load Principle alerts those who plan treatments for experiments to exercise caution when developing and testing agents that are visually and aurally "noisy" or complex.