RNA-Binding Proteins (RBPs) are proteins that bind to double or single stranded RNA molecules. In general, RBPs are thought to play a major role in post-transcriptional control of RNAs, such as: mRNA localization, mRNA stabilization, polyadenylation, splicing and translation. Hundreds of RBPs have been discovered in mammals. However, only a small fraction of these RBPs was mechanistically and functionally characterized thus far, leaving the question of why the cell has invested such a huge amount of resource to produce so many RBPs. One of the answers may come from the recently identified non-coding RNAs; it is now recognized that majority of our genome is used to code for non-coding RNAs (ncRNAs), including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). It is anticipated that many RBPs will be needed to modulate the biogenesis, modification and functional action of these large amount of ncRNAs in a cell.