Should the grooms parents be included on the wedding invitation

Should the grooms parents be included on the wedding invitation
Should the grooms parents be included on the wedding invitation

Yes. If the brides parents are listed, the grooms should be as well.
Its also acceptable to not list any parents by name.

Since we hosted [re: paid] for our own wedding, we worded it this way:

Jane June Doe
&
John Jared Doe
Along with their parents
Invite you to the celebration of their vows
... etc

should the grooms parents be included on the wedding invitation
We are paying for the chair covers, the beer, champagne and the alcohol...
And reharsal dinner

If I remember correctly, the groom's parents are included if they are paying for a portion of the wedding; the rehearsal dinner doesn't count because that is traditionally their expense anyway. So, if you are paying for chair covers, beer, champagne and alcohol, yes, you should be included. You are contributing to the cost of the wedding, which means you are a host - you should be listed. If the bride's parents pay for EVERYTHING you are (traditionally) not a host, and therefore get left off. However, in my book, both parents should be included because a wedding is celebrating two families coming together. I worded my invitations like this:

Bride (first and middle)
And
Groom (first and middle)
Together with their parents
Bride's parents (Mr. and Mrs. James Smith)
And
Groom's parents (Mr. and Mrs. John White)
Blah blah blah blah blah

My parents and my fiance's parents both contributed to the cost of the weding, so they were both on the invitation. If you go to a stationary store where invitations are ordered the books will have sample wording for you. Almost any wedding planner (book or person) will have it as well.

It shouldn't really be about how much money was contributed. If one set of parents are on the invite, both should be. If the grooms parents pay less (or are less involved) list their names second under the brides parents. Vice Versa could apply.
Basically, it should be all or none with parents names. You can't exclude only one set of parents.

Example:

Jane Doe
&
John Smith
Along with their parents
Mary and Todd Doe
And
Eliza Jones and Joe Smith
Invite you to...

Learning, I agree, but I seem to recall from when I worked at a stationary store the "traditional" way was to list the bride's parents only if they are the only one's paying. It seems to me most people do not follow this "tradition", however, as it is a bit, she we say, stuffy!

Jillian,
I'm sure you're right, I just can't imagine only listing one set of parents! Some can't afford to help... my mom couldn't do anything at all... but imagine the hurt feelings if she wasn't mentioned! I can see why "tradition" is breaking the mold. ;) We made it even by saying "parents" since DH and I paid 95%... and the invites didn't have enough room. LOL

I agree, it's rude to leave one parent off because of lack of financial contribution! To me, THAT is the bad etiquette!