You could legitimately congratulate someone on their engagement, I think.

After an engagement has been announced, sure!

Yes that's what I mean congratulating someone on their engagement. I probably would never be able to be that picky. I would have to stop talking. Although you're probably right Sue.

I agree with Lucille. I understand where you are coming from though.

I seem to recall that "Best wishes" are best for weddings or engagements, and not "Congratulations".

Here it is:

https://www.huffpost.com/entry/congratulations-to-a-bride_n_5617632

The Emily Posts would not "congratulate" a newly-engaged woman. "Best wishes" is more appropriate. You could, however, congratulate the newly-engaged man. He (usually) asked and achieved his desired outcome. I avoid the issue and just say "That's wonderful!"

Yes, it is a social faux pas to congratulate a woman who has become engaged since the actual inference isn't very good-as in high fives you nailed one. I have always wondered why it isn't the same for a man? I suppose the inequalities of the situation in the past, the female had to send delicate signals and wait and the male to choose. If she wasn't successful the woman needed deniability or she lost status-looked like a looser person. Poo on that.

I usually say something like "how exciting", "wonderful news", "so happy for you" or something along those lines, but I don't think most people would take offense to being congratulated.

Becoming engaged is an accomplishment. It means the two people involved have taken the time to get to know each other and have decided to commit to each other on a deeper level. Of course, I realize that isn't always true as some people just dive in without much thought, but I'm not talking about those folks.

Wondering if it is an exception for congratulating people who are graduating from advanced schooling where there is one graduation ceremony a year when the person will not finish until later in the year and they have a part in the graduation ceremony. While they may not finish they are more likely to do so.