From 6 months to almost 2 years. Just a little something to wear over a diaper or under panties to brighten up an outfit! Boys and girls can wear these. Has a matching headband too. We love the easy knit little bird that you make and sew on the border of headband and diaper cover. We stopped with one bird, but you could add more! This set is made with worsted weight yarns and US 8 knitting needles. A good baby shower gift!