The study of protein en masse, or functional proteomics, depends on the availability of full-length cDNAs in appropriate expression-ready plasmid vectors for protein expression and functional analysis. Recombinational cloning is a universal cloning technique based on site-specific recombination that is independent of the insert DNA sequence to be cloned, which differentiates this method from the classical restriction enzyme-based cloning methods. Recombinational cloning enables rapid and efficient parallel transfer of DNA inserts into multiple expression systems. This unit summarizes strategies for generating expression-ready clones using two of the most popular recombinational cloning technologies, now commercially available from Invitrogen (Gateway) and BD Clontech (Creator).