Microchipping is one of the best ways to insure that if your dog is picked up by any animal control agency or turned in by a good samaritan that you will get your dog back before it is adopted out or god forbid, euthanized! You must be sure to keep your contact info updated with the microchip company's recovery service of course. Also, as now almost all vets have universal scanners that will read the two main chips used in the states now, any stray that is brought in can be scanned--which is good in case someone finds your pet and tries keeping it for themselves--if they go to the vet and mention it was a stray, most likely the vet will scan it! It is definitely something to consider. As Dempsey'smama said, it is done by injection, is relatively painless (hurts about as much as a vaccination) and is well worth the cost. I would also call around to your local shelters or lowcost spay/neuter clinics and see if they offer special pricing-many times their chips also include prepaid registration of your recovery info (usually costs about ($13-15). hate to include this, as it is a bit morbid, but when I worked at an emergency clinic in SD, any stray that was picked up as deceased by animal control/disposal was also scanned to find its owner--awful to call someone and tell them their pet is dead, but better than never knowing what happened to them, I suppose....