The present invention provides methods for generating and identifying mutations in Caenorhabditis elegans. Disclosed herein are methods for introducing DNA into the C. elegans germline, methods for expressing DNA in the C. elegans germline, and methods for generating C. elegans mutants by using controlled mobilization of endogenous and heterologous transposons. Also disclosed are a transgene construct for expression in C. elegans and methods for inserting single copy DNA sequences into the C. elegans germline, and engineering mutations into the C. elegans genome.