Examines effectiveness of three different reading interventions in reading disabled second and third graders. Compares growth in phonological and orthographic processing and word reading. Finds the most significant mediator of intervention effects was initial differences in phonological and orthographic processing skills. Concludes that synthetic phonics facilitates skill in phonological analysis relative to analytic phonics and sight-word methods, but it does not transfer to gains in reading. Discusses implications. (RS)