The developmental and physiological complexity of a given organism is not governed by the sheer number of protein-coding genes. Instead, the numerous functional non-coding elements greatly expand gene regulatory modality and diversity functional reservoir. Using an interdisciplinary approach combining mouse genetics, genomics, cell and molecular biology approaches, we have identified a variety of functional non-coding elements, including miRNAs, long non-coding RNAs, and transposons. Not only do non-coding elements offer important developmental/physiological functions, but they also offer us a unique opportunity to discover new biological processes in mammalian development and disease.