I just installed a new lighting fixture in my living room and when I turned the electricity back on, the lighting fixture will not turn off. It is connected to a regular on-off toggle switch that worked perfectly well with the old fixture. I think I connected the wires correctly for the new fixture--white to white, and the fixture black wires I connected to the red wire and left the black bundle in the ceiling capped. Anyone know why the fixture won't turn off now? HELP!

Huh, sounds right to me. I would assume the red is the switch leg and the blacks the constant hots.
Are you SURE you didn't connect to the blacks in the ceiling?

I actually tried it both ways. I didn't know what the red wire was for and initially connected the black wires from the fixture to the black wire in the ceiling which eventually tripped the circuit breaker. I then capped the black wires in the ceiling and connected the black wires from the fixture to the red wire in the ceiling, but now it won't turn off. I even took the switch plate apart to see if there was a problem with the wires to the toggle switch, but they all look connected. Not sure what to do now...

Did you change any of the original splices in the ceiling?
What wires were on the switch?

I didn't make any changes to the splices - it's the same ones that worked with the prior fixture.

There was a black wire and a red wire attached to the toggle switch. The black was on one side, the red on the other.

Remove the switch and disconnect 1 wire to narrow down.

Something not right. If there is a red wire in switch there should be a white wire. If there is a black, red and white wire in switch, there should be other wires in switch box. Describe all wires in ceiling box. Pull switch and describe all wires there.