I would say it depends on what is sore, how sore it is, and what you are working out. If your legs are sore you are ok to work out your upper body.
Also, how sore are you? If the soreness is really deep (like you will be sore for more than a day) you probably should rest a day or work a different body part.
And finally, it depends on what the rest of your training week is like. If you had a hard practice and your legs are sore and you are going to have a hard practice the next day you might want to lay off.
Don't forget too, if its during season train for muscle conditioning, and not mass.