The ability to culture and maintain postnatal mouse hippocampal and cortical neurons is highly advantageous, particularly for studies on genetically engineered mouse models. Here we present a protocol to isolate and culture pyramidal neurons from the early postnatal (P0-P1) mouse hippocampus and cortex. These low-density dissociated cultures are grown on poly-L-lysine-coated glass substrates without feeder layers. Cultured neurons survive well, develop extensive axonal and dendritic arbors, express neuronal and synaptic markers, and form functional synaptic connections. Further, they are highly amenable to low- and high-efficiency transfection and time-lapse imaging. This optimized cell culture technique can be used to culture and maintain neurons for a variety of applications including immunocytochemistry, biochemical studies, shRNA-mediated knockdown and live imaging studies. The preparation of the glass substrate must begin 5 d before the culture. The dissection and plating out of neurons takes 3-4 h and neurons can be maintained in culture for up to 4 weeks.