Reading fluency is commonly defined as reading accurately at a quick rate with appropriate prosody--a simple sounding definition. In fact, this definition hides complex processes and skills needed to produce the seemingly effortless performance of a fluent reader. Using both theory and empirical research, the presence and role of underlying processes and knowledge such as decoding fluency, processing speed, vocabulary, letter sound fluency, and sight word fluency are discussed. In doing this, we explain the elements needed for fluent reading and how they relate to each other in a multilayered fashion in young readers, and discuss the implications of this model in the development and assessment of reading fluency. (Contains 4 figures and 1 table.)