What would be a reasonable solution to illegal immigration from Mexico?

Obviously this is a subject of much controversy, but potentially an area of great opportunity as well. Illegal immigration will not end, so is there a mutually beneficial solution? To me, the root of the problem is in the existing conditions that drive Mexicans to seek a better life in the US. There is an argument they drain resources being here illegally, and an argument if immigration policies are reformed we could increase the taxable base to pay for the consumed resources. What do you think could help?