Weed and Feed won't help if the dandelions are already there - it only works as a pre-emergent- has to be applied before the weeds germinate (early spring). Around here they say to apply it as soon as the forsythia bloom. My dh ( a weed hater and lawn fanatic) has one of those handy little tools that you dig in at the base of the weed and it has a "V" shape that pulls it out root and all. That would be a lot of work if you have a yard full though. We usually let our mower "mulch" the grass and leave it on the lawn, but another little trick if you have some dandelions that you don't want, is to use your bag attachment on your mower when mowing them so that you are not just spreading their seeds all over the lawn and making the problem worse. Hope this helps.