I need to install a ceiling light in our bedroom. I have a single light switch and four outlets. One of the outlets is operated by the light switch. I have the following wires coming into the light switch box: three white wires/capped, three copper ground, three black/capped with a fourth pig tailed to the light switch and a red to the light switch.

With this configuration can I run Romex down from the attic and the ceiling fixture to the light switch box for power? Of course adding a dual switch, one for the outlets and one for the ceiling light? If yes, how should I wire the romex to the switch?

Thanks.

Presumably you have a single gang switch box. Remove switch box and install a two gang old work box. Rewire everything just as it is now but add another pig tail to the black wire bundle. Connect white of ceiling light to white bundle. Connect pig tail to new switch and connect black of ceiling light to new switch. Connect ground to ground bundle.