Explicit knowledge can be defined as conscious knowledge about a language that a learner is able to articulate in some way. This type of knowledge is generally contrasted with implicit knowledge, which is tacit, intuitive, procedural, and is only observable during communicative acts. In this presentation, Dr. Kenneth Richter will discuss how both types of knowledge can facilitate interlanguage development; consider second language teaching from the perspectives of consciousness raising and "noticing"; and examine the role of language assessment.