Age responsibility should start.

As soon as they can crawl out or the crib & mess it up. If you don't start from the very beginning they'll resist the whole time.

I think children should start to tidy their toys in their room by about 2 years old. I think the parent should tidy their room and get them to join in as if its a game, so they learn to tidy up when they are finished playing with their toys at an early age. I think if they gradually get use to it, it will be helpful to them and their parents when they are older. I don't think childrens rooms should be completly clean(with no toys on the floor) because they learn by making a mess and tidying up too. ~Joeys wife

I would say as soon as possible. As soon as they are able to pick things up and put it in some place. At first you can let them dump all the toys into a basket or box after they are done playing and slowly work towards better cleaning. From my experience, the earlier you start, the easier it is. When they are younger you will have to be with them to make sure they do it. The right age? As a mother you should be able to judge that - anywhere between the age of 1 and 3.

I started making my son clean his room at age 2 with me in there with him to supervise. I made him put all of his toys back in the toy box and we made it a game while we sing the "clean up" song. Now, I didn't expect him to make his bed or dust or any of that of course. Now he is 4 and I expect that he pick up his own toys, at least put the blanket ON his bed if they are tossed off of it, and put books away. I still help with detailed things, but he is expected to keep it neat. Every night before bed he picks up.

I started the clean up responsibility as soon as my now 3 year old started to walk...now he picks up without me telling him too. As long as he knows where things go, he will put the toys in his room away. It has been a ritual for 2 years to clean up after you're done playing and to clean up all your toys before bed. so, at what do I feel? Not so much an age as when they start walking.