I think your chilli's have been on the vine too long, you are supposed to pick when they are green at least that how i pick them here in SC.

Is there a red or yellow chili plant somewhere in the area? Cross pollination might be taking place. If they're green for a while and then turn yellow, you're picking them too late. Are you sure you bought a green chili plant?

Looking at the picture, you may have just gotten a genetic abnormality. If the chilis taste the way they should, then that's the case and replanting is necessary (though some breeds are red, yellow or orange normally). If they taste off, as well as being yellow, then you may be picking late or their may be cross-pollination with other peppers (even sweet peppers) in your garden or a close neighbors.

Either left it too long or not long enough. what color is it supposed to be? If its supposed to be green, then you left it too long. IF its supposed to be red you need to leave it longer.

I believe all chilis start green, turn yellow, and then red. I'd pick one and leave it on your counter top and see what it does.

It's just a variety that happens to be yellow. Not sufficiently rounded on the end to be a jaloro (yellow jalapeno). Looks more like a NuMex Eclipse, perhaps one of the Peruvian aji varietals ( Aji Cito, Aji Amarillo, Aji Norteno). Datils also tend to be orange or yellow. In fact, there may be a hundred varieties that produce a yellow pepper similar to the one pictured. I had some Tequila Sunrise peppers last year that looked pretty much like this one. Can't really say without more info on size of the pepper and the plant, color of the flower, how hot it is, etc. Good sites for chili pepper identification: http://www.g6csy.net/chile/ http://www.rachelssupply.com/pepper.htm http://www.chilepepperinstitute.org/documents/catalogrevised08.pdf

looks like a young habanero