Drawing on results from informal reading inventories and studies of oral reading behavior, a theory is presented to describe the process of learning to read. Reading is seen to be broader than a skill and more like a repertoire with many abilities, aptitudes, and special accomplishments performing in concert. This repertoire is acquired in four developmental cluster periods where the skills to be learned within a cluster are acquired in a nonlinear fashion. Linearity is important in the period between clusters as the reader struggles to achieve new structures of knowledge. This linearity between clusters supplies guidance and support when the learning challenge is greatest, that is, during the time of breaking out of one developmental period and breaking into another. (Author/AA)