The relationship between language, literacy, and communication is powerful. Speaking, listening, reading, and writing develop together; therefore, meaningful language, literacy, and communication opportunities should be embedded into every part of a student’s day. Research tells us that when adults create rich language and literacy environments and respond to a child’s communication in specific ways, they can boost that child’s emergent language and literacy development and increase the likelihood of future academic success. (www.hanen.org)
The acquisition of language and literacy skills is social. It happens because young children want to interact and communicate with others. Literacy occurs during meaningful interactions, experiences, and activities; however, children differ in how and how fast they learn. Some language and literacy learning happens naturally during play and everyday experiences, and some depends on explicit instruction from observant and sensitive adults. Differences in children’s home language and culture can affect literacy development. Classroom literacy experiences should allow for and value these differences. Language and literacy are connected from infancy onward. Speaking, listening, reading and writing develop concurrently rather than sequentially. (www.highscope.org)
The American Speech-Language and Hearing Association (ASHA) states in its position statement that the connections between spoken and written language are well established in that (a) spoken language provides the foundation for the development of reading and writing; (b) spoken and written language have a reciprocal relationship, such that each builds on the other to result in general language and literacy competence, starting early and continuing through childhood into adulthood; (c) children with spoken language problems frequently have difficulty learning to read and write, and children with reading and writing problems frequently have difficulty with spoken language  ; and (d) instruction in spoken language can result in growth in written language, and instruction in written language can result in growth in spoken language.
As with difficulty in learning to listen and speak, difficulty in learning to read and write can involve any of the components of language—phonology, morphology, syntax, semantics, and pragmatics. Problems can occur in the production, comprehension, and awareness of language at the sound, syllable, word, sentence, and discourse levels. Individuals with reading and writing problems also may experience difficulties in using language strategically to communicate, think, and learn. These fundamental connections necessitate that intervention for language disorders target written as well as spoken language needs.
Additional resources from ASHA:
ASHA’s Position Statement on Literacy: http://www.asha.org/docs/html/PS2001-00104.html
ASHA’s Literacy Gateway: http://www.asha.org/publications/literacy/
Building Literacy Skills K-2: http://www.asha.org/uploadedFiles/Build-Your-Childs-Skills-Kindergarten-to-Second-Grade.pdf
Building Literacy Skills 3-5: http://www.asha.org/uploadedFiles/Build-Your-Childs-Skills-Third-to-Fifth-Grade.pdf