I buy a small pair of these when my daughter as a couple of month old . they seem to work great ! I even buy some for a friend as a shower gift and buy more in the next size up for my daughter . unfortunately , my doughter , who be now 7 month , can still wiggle she way out of she sock , even with the sock-on on ... maybe she foot be just smaller than the average baby , but I doubt it , because she be in the 85th percentile for both height and weight .