In certain situations boasting about one’s achievements is a necessary evil (I’m British, OK?). It’s a delicate thing to do correctly and there are strategies to successfully avoid the situation completely[1].

When you must brag, however, research has shown in what circumstances a person’s boasting comes across as self-absorbed arrogance and when it comes across as justified in the context of the conversation.

The crux of it: context is everything when it comes to boasting. If Avi’s friend raised the topic of the exams, Avi received favourable ratings in terms of his boastfulness and likeability, regardless of whether he was actually asked what grade he got. By contrast, if Avi raised the topic of the exams, but failed to provoke a question, then his likeability suffered and he was seen as more of a boaster.

In other words, to pull off a successful boast, you need it to be appropriate to the conversation. If your friend, colleague, or date raises the topic, you can go ahead and pull a relevant boast in safety. Alternatively, if you’re forced to turn the conversation onto the required topic then you must succeed in provoking a question from your conversation partner. If there’s no question and you raised the topic then any boast you make will leave you looking like a big-head.

However, as noted at Mind Hacks, this study was conducted in Israel and there are obviously going to be regional variations:

I’ve informally noticed that the social acceptability of ‘talking oneself up’ varies greatly between countries – from the USA, where moderate self-praise is standard social currency, to the UK, where it is only acceptable when followed by a self-deprecating comment or joke, to Sweden where it is only acceptable when one is threatened by armed men or the future of the world hangs in the balance.

[1] Ben Casnocha suggests:

In a group setting with impressive people (conference, dinner party, etc) have a third person introduce each person instead of self-introductions. You can’t brag about yourself. A third party can.