Recognizing the words in a text is an important part of skilled reading and a source of difficulty for many children who are problem readers and for many adults who have acquired language disorders as a result of stroke or other brain injury. An important question for research on word recognition is when are words decoded wholistically as complete units and when are they decoded compositionally by analysis into sub-lexical units. The proposed research addresses this question for words which are morphologically complex, that is words which contain more than one morpheme. The general hypothesis being explored is that high frequency words will be analyzed wholistically while lower frequency words will be analyzed compositionally. In addition, it is expected that whether or not a lower frequency word will be processed compositionally will depend on the relationship between the frequency of the word and the frequency of its parts and the degree to which the meaning of the word is predictable from the meaning of its component morphemes. It is also expected that there will be developmental differences in how these words are processed with younger and less skilled readers relying more heavily on a compositional strategy than older and more skilled readers. These hypotheses will be explored in a series of studies using lexical decision and naming tasks with skilled adult readers and children of various ages and reading abilities. The long-term goals of this research are to understand how word recognition is accomplished in skilled reading, how word recognition skills develop, and why certain children have difficulties with word recognition. Understanding how morphologically complex words are processed is an important step in reaching these goals.