Since I am originally from India, money is the most appreciated gift :-) given that Indian weddings are elaborate and expensive multi-day affairs. However, other cool gifts like jewellery will also be appreciated. As others have noted, Indians are fixated with gold, specifically 24 crt which is hard to get in NA. As for dressing, things have got very modern so western attire is fine. I would also recommend a salwar/kurta as they are easy to wear and you can get some very nice stuff. A novice wearing a saree can result in a wardrobe malfunction plus the practical difficulties of dancing in a sari. You will need multiple outfits like a bollywood production, one for each day. Think business casual for the pre wedding events and a very dress kurta for the main wedding. Indians also eat very late at weddings, typically it is the last thing they do at a wedding after all the drinking/dancing (assuming they serve alcohol in which case it will likely be open bar), so you may want to eat a snack before going. If the wedding is at a banquet hall, noise regulations means that it will wind up at 11-12pm for the reception. In a hotel, they could go later. Depending on the wedding, in a banquet hall there could be upwards of 500 guest - I believe we had 650 at our wedding and that is not unusual. If in a swanky hotel it will be a more manageable 100-200. Other posters advice above are all good too. Practice your bollywood dance moves and have fun.