In this project we are seeking to define a unique new approach to the challenges of artificial intelligence, one that draws its inspiration from the biological phenomenon of development. Our central contention is that by understanding the processes by which animals "grow up" cognitively, we will be able to come much closer to our ultimate goal of creating virtual creatures that are as clever and adaptable as their real-life counterparts. After a careful analysis of the biological literature, we have implemented a novel behavior architecture for our virtual creatures, one that is grounded in what we see as the key computational lessons of development. Foremost amongst these lessons is the concept of Specialized Learning Tools, a domain-specific means of organizing the learning of our creatures so as to efficiently manage and integrate diverse competencies in a unified behavioral context.