To uncover the structure of the underlying genetic networks during early embryogenesis and to identify new components and pathways that participate in these key events, I have set up a system to systematically test for enhancing and suppressing interactions using RNAi in large-scale. At the initial stage of this project, I used 24 temperature sensitive (ts) alleles whose strong loss-of-function phenotype affects the early embryo, and an average of 500 selected genes against each ts allele. From this work, I acquired and analyzed over 100,000 RNAi experiments and identified over 560 high confidence genetic interactions. The analysis of the data revealed new functions for genes, uncovered pathways previously not known to operate in the embryo, and showed new connections between pathways that are potentially buffering each other. I confirmed some of these interactions by quantification and further studied them by detailed phenotypic analysis. These results granted the expansion of the project and with a team effort we are extending our screen and analysis to the whole C. elegans genome.