Cellular RNAs containing double-stranded RNA (dsRNA) structures are subject to A-to-I RNA editing by the adenosine deaminases that act on RNA (ADARs). While A-to-I editing can alter mRNA coding potential, most editing is observed in non-coding sequences, the function of which remains poorly characterized. Using a dsRNA immunoprecipitation and high-thoughput sequencing (dsRIP-Seq) approach, we identify 1523 expressed A-to-I edited regions and characterize their expression during Caenorhabditis elegans development. We observe that edited regions are highly expressed in early development and are closely associated with protein-coding genes. Edited dsRNA structures give rise to abundant small interfering RNAs (siRNAs) that are negatively correlated with ADAR expression and regulate the developmental expression of associated genes. Overall design: RNA-Seq of total RNA and RNA immunoprecipitated with a dsRNA-specific antibody (dsRIP) from whole C. elegans at four stages of development: embryos, early stage larvae (L1-L2), late stage larvae (L3-L4), and young adults.