The Tol2 transposable element was originally found in the genome of the Japanese medaka fish (Oryzias latipes). Tol2 contains a gene encoding an active transposase that can catalyze DNA transposition in vertebrate cells. In zebrafish, Tol2 generates genomic integrations in the germ cells very efficiently. By using the Tol2 transposition system, we have developed important genetic methods including transgenesis, gene trapping, enhancer trapping, and the Gal4-UAS system in zebrafish. In this chapter, we describe how these methods can be performed.