How can I get grass to stop growing in my vegetable/fruit garden?

How can I get grass to stop growing in my vegetable garden? We paid to have somebody rototill it but obviously they did not do a good job I guess. The vegetables are coming up well, but there is a lot of grass coming up too. How can I kill all the grass without killing the veggies and melons? If it matters there are peas, garden beans, wax beans, cantaloupe, green mellon, watermelon, crenshaw melon, cucumbers, summer squash, zucchini, peppers, hungarian hot peppers, jalapeno peppers and habenero peppers in there. I know one obvious way would be to pick out all the grass by hand, but that seems like a ton of work. I am wondering if there is an easier way?