DD is two and a bit and, apart from a heady couple of weeks when she was about six weeks old, has never slept through. I mean, she does sleep five hours a night from about 7 pm to midnight, but then we go to bed at midnight and she wakes up every couple of hours, so although I know that's technically sleeping through, I don't think it really counts 
Everyone told me it would get better when she was walking, which she did late, but it didn't. We have night weaned. She eats a good amount at three meals and (at least) two snacks a day. She is stimulated during the day. We have now dropped all naps. She has a decent bedtime routine (though that's all changed recently) and is perfectly capable of self-settling. I do not know what else there is!
It is manageable (particularly as DH now does all night wakings
) because she just wakes up and asks for a cuddle or a drink (she has sippy cups by the bed) and then goes back to sleep but I am starting to wonder if she will in fact ever sleep through the night ... ?