Alternative splicing is common amongst eukaryotes and is regulated in part by a large number of proteins. Two large protein families have emerged as general regulators of alternative splicing in eukaryotes: serine/arginine-rich (SR) proteins and heterogeneous ribonucleoproteins (hnRNPs). mRNAs that encode SR and hnRNP proteins are often alternatively spliced and this thesis focuses on the regulated alternative splicing of mRNAs that encode SR proteins in the nematode Caenorhabditis elegans. I found that six of the seven C. elegans rsp mRNAs (known as SR mRNAs in other eukaryotes) are alternatively spliced. Such splicing leads to one of two types of mature rsp mRNAs: (i) rsp mRNAs that encode functional RSP proteins, termed rsp(+) mRNAs, or (ii) rsp mRNAs that introduce premature termination codons (PTC), termed rsp(PTC) mRNAs. PTC-containing mRNAs are substrates for the nonsense-mediated mRNA pathway (NMD) and are rapidly degraded in wild type. I investigated if and how rsp splicing patterns are regulated in three ways. (i) I investigated if rsp splicing patterns are developmentally regulated. Early in development, a drastic decrease in several rsp mRNAs occurs that correlates with an increase in the proportion of rsp(PTC) mRNAs. I suggest the increase in the proportion of rsp(PTC) mRNA is a means to remove excess rsp mRNA since PTC-containing mRNAs are rapidly degraded in wild type. (ii) I investigated if RSP proteins autoregulate their own splicing patterns. I found overexpression of an RSP protein affects the splicing pattern of its own mRNA by increasing the proportion of rsp(PTC), and reduction in RSP protein levels decreases the proportion of rsp(PTC) mRNA. (iii) I investigated if one or more RSP proteins can regulate the splicing pattern of a different rsp pre-mRNA. I found RSP-2 and RSP-4 regulate the splicing pattern of rsp-5 mRNA, and RSP-4 regulates the splicing pattern of rsp-7 mRNA. I hypothesize these regulated splicing events are examples of post-transcriptional gene regulation. Splicing to increase or decrease the proportion of rsp(PTC) mRNA is therefore a means to fine-tune the levels of rsp(+) mRNAs.