This thesis examined whether the Early Learning Measure (ELM) could predict outcomes for children with severe autism following Intensive Behavioral Intervention (IBI). The ELM assessed skills in four domains monthly for the first four months of IBI. Children were grouped based on mastery of the ELM. Outcomes on measures of adaptive behavior and cognitive functioning were assessed at entry, 6 months, and 12 months. Results showed that mastery of the ELM correlated with better outcomes and that expressive labeling ability may distinguish children who benefit from IBI. However, combining ELM mastery with baseline characteristics provided the best prediction of outcomes. Determining predictors can help maximize resources and prevent ineffective treatment.