1. There are many great places for outdoor lovers to wed: think botanic gardens, beaches, parks. Animal lovers might marry at a zoo or aquarium -- often unforgettable wedding sites. (Okay, so they're not completely PC, but at least the money'll go to take care of the place.)

2. Use recycled paper for your invitations. Send single-sheet invites and reply postcards, or one-piece postcard invites that ask guests to RSVP by phone or email so you don't have to use additional paper and stamps for outer envelopes and response cards. Also, avoid using tree-wasting tissue inserts.

3. Let it be known that you'd like guests to make donations to your favorite causes instead of buying you wedding gifts. Or at least register at The Knot where we let guests give a contribution to a charity of choice instead of wasteful gift wrap.

4. Wear a natural fiber, like cotton or silk, on your wedding day. Brides, if you're having a dress made, make sure no synthetic materials or chemical dyes are used. Or, think about wearing a pre-worn wedding gown.

5. For wedding-day makeup, make sure to use cosmetics made by cruelty-free companies.

6. For bridesmaids and groomsmen, choose eco-friendly gifts such as binoculars, nature books, globes, birdhouses, flower boxes, or naturally-made candles and soaps.

7. Play nature tapes for pre-ceremony music -- whale or dolphin sounds, wind, water, wolves howling, birds singing. It'll be a beautiful backdrop for a meaningful ceremony.

8. If you have animal friends -- family dogs, a pet snake -- include them in the ceremony procession.

9. After the ceremony, have guests toss eco-friendly bird seed or biodegradable rice instead of real bird-killing rice.

10. If your guests must travel farther than walking distance from ceremony to reception site, arrange for carpools to save gas. Get to and from your wedding with environment-friendly, fuel-free transportation like bikes, roller skates, or a horse and buggy.

11. Use potted living plants as centerpieces, instead of cut floral arrangements. Asters, impatiens, mums, dahlias, tulips, daisies, hyacinth, and miniature roses can all be replanted. Invite guests to take them home to their backyards or window boxes.

12. Collect shells, rocks, or pinecones to create tactile, natural table centerpieces.

13. Give guests tree saplings, bulbs, seeds, or small potted plants or herbs as wedding favors. Forego favors altogether and make a donation to the World Wildlife Foundation, World Reserve Foundation, Sierra Club, or another group of your choice.

14. Use silverware, china, and linen for the reception meal, instead of plastic utensils and paper cups, plates, and napkins. Stay away from decorations like streamers, balloons, and confetti.

15. Use washable towels, natural soaps, and recycled toilet paper and tissue in the restrooms at the reception site.

16. Plan a vegetarian menu, or at least keep it free of unfriendly foods like milk-fed veal, dolphin-killing tuna, or caviar.

17. Support local farms, orchards, and vineyards by buying your produce and wine from them.

18. Don't let reception food go to waste: Take leftovers to a local soup kitchen or shelter and help feed the less fortunate.

19. Make sure the dry cleaner who cleans the wedding dress after your big day doesn't use any harmful or toxic chemicals.

20. Enjoy the great outdoors with an eco-honeymoon. Visit the rain forest you've been working to save -- Costa Rica, maybe. Or spend the time doing a good deed together, like building houses with Habitat for Humanity or planting trees in a forest.