The nuclear lamina is a filamentous structure, composed of lamins, that supports the inner nuclear membrane. Several integral membrane proteins including LBR (lamin B receptor), LAP (lamin-associated polypeptide) 1, and LAP 2 bind nuclear lamins in vitro and may influence lamin function and dynamics in vivo. Results from various studies suggest that lamins may have major functions in DNA replication, nuclear-envelope assembly, and nuclear-envelope growth. Here we discuss experimental evidence that supports these hypotheses and consider how interactions between lamins and other nuclear-envelope proteins, in particular LBR and LAP 2 isoforms, may contribute to or alternatively mediate these functions of the lamina.