Like so many over Memorial Day weekend, Rachel McAdams participated in a family wedding.
The Aloha actress was the maid of honor to her younger sister, Kayleen, and just like in every romantic movie she's been in, the gal was filled with emotion.
An eyewitness tells ET that Rachel laughed and cried a few tears during her sibling's big day. The source also says she looked genuinely happy for her sister and was a dutiful maid of honor who tended to the bride's needs, including holding her bouquet during the ceremony, making sure the wedding dress was in perfect form and fetching a handbag before the post-ceremony photos.
Hmm, will Kayleen repay the maid of honor duty for Rachel soon? After all, the 36-year-old beauty was recently rumored to be dating her Southpaw co-star Jake Gyllenhaal. But alas, Gyllenhaal told Ellen DeGeneres while appearing on her show last month that he's single "for now."