How do you kill crabgrass?

I've found that Crab Grass is best controlled by using one of two products. "Advanced Lawn Care" (made by Bayer) or "Weed N Hoe" made by Monterey Chemical Company. Both are equally good. You should buy the concentrate and mix according to directions for your geopgraphical area. These chemicals are "selective," meaning you can spray all over your lawn. It will not harm your grass. It only kills the weeds. I've also found that if the weeds are not dying as soon as they are supposed to, I reapply the chemical about a month later but mix it a little heavier than the instructions call for. I have an absolutely weed-free lawn. You should also use a 16-16-16 feed on your lawn. Do this every third week. It will keep it healthy and green. It is inexpensive. Try your local OSH. GOOD LUCK!!