We have been working to apply in vitro selection to isolate novel RNA-binding peptides. To do this, we use mRNA-protein fusions, peptides covalently attached to their own mRNA. Here, we report selection protocols developed using the arginine-rich domain of bacteriophage lambda-N protein and its binding target, the boxB RNA. Systematic investigation of possible paths for a selection round has allowed us to design a reliable and efficient protocol to enrich RNA-binding peptides from nonfunctional members of a complex mixture. The protocols we have developed should greatly facilitate the isolation of new molecules using the fusion system.