A traditional Pakistani wedding celebration lasts four days. On the first day, the bride and groom�s families wear yellow and celebrate separately. On the second day, the groom�s family delivers the wedding dress to the bride�s house and the bride�s family delivers the groom his wedding attire. The bride's hands and feet are painted with elaborate henna designs.
The third day is dedicated to the wedding rites and ceremony where the paperwork is signed in the presence of an Islamic priest. After the vows are said, the Koran is held over the bride�s head and she joins her husband�s family (Nikkah). This is the bit you will probably be invited to.
The bride wears a decorative red scarf and dress, and her hands and feet are decorated with henna designs. She also wears jewels handed down from her mother and the groom�s mother. The groom wears a ring of flowers around his neck as well as the traditional turban.
On the final wedding day, the couple hosts their first dinner at the groom�s home, inviting all their family and friends for a wedding feast.
Depending on your level of friendship and how strict they are to tradition, I think you can pretty much wear what you would to any other formal wedding. I would avoid wearing red though. If in doubt, ask someone close to the family who will know for sure and can advise.