Theories of reading development generally agree that, in addition to phonological decoding, some kind of orthographic processing skill underlies the ability to learn to read words. However, there is a lack of clarity as to which aspect(s) of orthographic processing are key in reading development. We test here whether this is orthographic knowledge and/or orthographic learning. Whereas orthographic knowledge has been argued to reflect a child’s existing store of orthographic representations, orthographic learning is concerned with the ability to form these representations. In a longitudinal study of second- and third-grade students, we evaluate the relations between these two aspects of orthographic processing and word-reading outcomes. The results of our analyses show that variance captured by orthographic knowledge overlaps with that of word reading, to the point that they form a single latent word-reading factor. In contrast, orthographic learning is distinctive from this factor. Further, structural equation modeling demonstrates that early orthographic learning was related to gains in word reading skills. We discuss the implications of these findings for theories of word-reading development.