How do you know when a bell pepper is ready to be picked?

[JollyRoger]

Do they need to be a certain size or full color? I have green, red and yellow growing. Some have changed color and some are still green when they should be red or yellow.

 

[saaanen]

If you have red, they should be red. If you have yellow, the should be yellow. If you have green, they should be green.

 

[doug]

When they are full and firm.