It is I, Grammar Police

In school we learn that we should put the other person first and say "Bob and I went to the store" instead of "Me and Bob went to the store." Many people get this drilled into their heads and will over-correct and use "Bob and I" even when it's supposed to be "Bob and me." (On the radio the other day I heard someone talking about "the dedication of my partner and I.") The trick people will tell you is that you should take the other person out and see which pronoun to use. For example, you would say "Sally sat down next to me," so if Bob was there too you say "Sally sat down next to Bob and me."

Most people probably know this. We have grammar threads on Two Peas every once in a while, and it seems like this often gets brought up. People complain about the incorrect usage of "Bob and I" when it should be "Bob and me." I know, I notice it too.

But how about this construction?

"This is Bob and I."
"The winners of the contest were Sally and I."
"That's my mother and I in front of the cabin at the lake last year."

Many people would probably think that they should say "This is Bob and me" rather than "This is Bob and I." But it is grammatically correct to say "This is I." (If you want to get technical, the "be" verb takes the nominative case.)

It sounds awkward and stilted. Nobody talks that way. I don't talk that way. (Though I do say "This is she" when I answer the phone, even though I think it sounds doofy.) But it is correct.

Generally, I tend to be much more of a descriptive grammarian than prescriptive. Feel like ending a sentence with a preposition? Be my guest. Want to boldly split infinitives that no one has split before? You go right ahead. I'm not saying that everyone should go around saying "This is I." That's not my point. The point is that it's not wrong if someone says "This is Bob and I."

Now, anyone want to know the difference between "lie" and "lay"?