Emerin, a conserved LEM-domain protein, is among the few nuclear membrane proteins for which extensive basic knowledge--biochemistry, partners, functions, localizations, posttranslational regulation, roles in development and links to human disease--is available. This review summarizes emerin and its emerging roles in nuclear "lamina" structure, chromatin tethering, gene regulation, mitosis, nuclear assembly, development, signaling and mechano-transduction. We also highlight many open questions, exploration of which will be critical to understand how this intriguing nuclear membrane protein and its "family" influence the genome.