Alternative splicing regulation has been shown to be critically important for several developmental pathways. It is particularly prevalent in the testis, which is the site of an extensive adult developmental programme. Alternative splicing is controlled by a splicing code, in which transcripts respond to subtle cell type-specific variations in positive and negative trans-acting RNA-binding proteins according to their unique set of binding sites for these proteins. Because of their unique combinations of cis-acting sequence elements, specific transcripts are able to respond individually to this code. In this review, we discuss how this code may be deciphered in germ cells to mediate a splicing response.