Social etiquete regarding an invitation
My husband and I have received an invitation to our neighbor's daughter's 15th birthday which I believe is a grand party of thanksgiving to the Lord. What is the name of such a celebration and are we obligated to go to the event since we received an invitation, or would a gift be appropriate?
3 Answers
If you wish to know more about the party itself I would search previous threads containing quinceañera (the 15 year old gir). Some contain links to descriptions of the party and the social significance.

Hola, Ruth! Welcome to SpanishDict.
I have a few questions for you.
1) Have you considered asking on Yahoo Answers? I think that forum may be of more assistance than this one. SpanishDict specializes in Spanish/English learning and teaching. Y!A has many sub-categories where you can post a question like yours.
2) What is a grand party of thanksgiving to the Lord?
Fiesta de quince años. Or simply: "unos quinceaños". It would be nice of you if you go to the event with a present.