YES, it is possible to get ample protein for athletic performance on a vegetarian or vegan diet. There are plenty of ways to get your essential amino acids from sources other than dead animals.
If you are a lacto-ovo vegetarian, obviously eggs and/or dairy products (cheese, yogurt, etc.) are still good sources of protein. Contrary to popular belief, even vegans have plenty of resources for protein, which are obviously available for anyone on a vegetarian diet or not. Proteins sources derived entirely from plants include, but are not limited to:
The "meat alternative" market is growing steadily as more and more people, vegetarian or not, seek out healthier fare. Popular brands include Boca, Gardenburger, Tofurkey, Yve's, Quorn, Veat, Health is Wealth, and store brands such as from Whole Foods or Trader Joe's. (While some of these meat alternatives are free from animal products, others may still contain egg or dairy derivatives; check the nutrition labels.)
There are also a great deal of commercial "protein" bars out there, but depending on how strict you wish to be, keep in mind they are not necessarily vegetarian. Check the ingredient labels, and you may be surprised to find gelatin, hydrolyzed collagen (gelatin), whey protein, or even fish oil.
You may have heard about "protein-combining," and the idea that vegetable proteins are not as "complete" as those derived from animals. Remember that as long as you are eating a wide variety of foods (as is necessary in any diet, not just for vegetarians), you will be able to get all of the amino acids you need without having to worry about combining foods.
Evan Keraminas