My son had a child 18 years ago who was adopted. I would like to locate my grandchild to see if he would like to meet us. How do I go about doing that?

You can't.

Well, not easily, anyway. You can hire a private detective or post on reunion websites, but that's about ALL you can do.

YOUR SON has many more options, however. Why is he not searching?

I find it unusual that it was a closed adoption 18 years ago. Most adoptions were open or semi-open by then. Were there extenuating circumstances to make the adoption closed?

I would strongly urge you to use the reunion sites. You do not have any clue what an attempt to contact him will mean. It could be a happy reunion or it could be devastating to him and his family. You are NOT his family, you are simply someone who shares a biological connection with him and you need to accept that.

If he knows he was adopted and is curious about connecting with his biological relations, then he will also use the reunion sites.

With closed adoption it is hard, hiring an investigator could be the most promising. But you can also post on many of the dozens of adoption web sites and hope to connect, assuming he knows he is adopted and wants to meet.