They can get it from beans and legumes easily.

Milk, Fish, and Eggs.

vegetable are high in preotein to begin with ex. - spinach

Protein overdoses occur much more frequently than protein deficiencies. Even if one abstains from animal products, one would have to go out of one's way to get an inadequate amount of amino acids. www.nutritiondata.com is an excellent source to find out what amino acids are in a particular food. Try looking up "black beans" on the website. That is one of many protein sources that comes from plants and contains large quantities of all nine essential amino acids.

1) "Dietary sources of protein include meats, eggs, nuts, grains, legumes, and dairy products such as milk and cheese. Of the 20 amino acids used by humans in protein synthesis, 11 "nonessential" amino acids can be synthesized in sufficient quantities by the adult body, and are not required in the diet (though there are exceptions for some in special cases). The nine essential amino acids, plus arginine for the young, cannot be created by the body and must come from dietary sources. Most animal sources and certain vegetable sources have the complete complement of all the essential amino acids. However, it is not necessary to consume a single food source that contains all the essential amino acids, as long as all the essential amino acids are eventually present in the diet: see complete protein and protein combining." Source and further information: http://en.wikipedia.org/wiki/Protein_(nutrition%29 So, if vegetarians just don't eat meat, there have still protein in eggs, nuts, grains, legumes, and dairy products. If they don't eat eggs and dairy products (vegans), there have still protein in nuts, grains, and legumes. 2) "Sources of complete protein: Complete proteins can be found in meals prepared with a mix of protein foods that provide all the essential amino acids, such as: lentils and rice, bean burrito, peanut butter and jelly sandwich, vegetables and rice. Some foods contain all the essential amino acids on their own in a sufficient amount to qualify as a "complete protein". Complete protein foods that also obtain the highest possible PDCAAS score of 1.0 are certain dairy products, egg whites, and soy protein isolate. Other foods, such as amaranth, Aphanizomenon flos-aquae, blood, buckwheat, hempseed, meat, poultry, soybeans, quinoa, seafood, and spirulina also are complete protein foods, but may not obtain a PDCAAS score of 1.0." Source and further information: http://en.wikipedia.org/wiki/Complete_protein 3) "Protein combining (also protein complementing) is a controversial theory that vegetarians, particularly vegans, must eat certain complementary foods like beans and rice together in the same meal. The purpose of protein combining is to ensure that plant foods with incomplete essential amino acid content combine to form a complete protein, meeting all amino acid requirements for human growth and maintenance. Many health organizations now consider protein combining within the same meal to be unnecessary. Instead they recommend that vegans consume a variety of plant foods to ensure that all protein requirements are met." Source and further information: http://en.wikipedia.org/wiki/Protein_combining

Ask this guy. http://vegetarianstar.com/2008/11/30/mac-danzig-food-voyeurism-you-know-you-want-some/

You eat complete proteins. Such as beans and brown rice or Tofu & some other whole grain together. I eat small amounts of dairy & eggs. I also eat protein pasta.Lots of soy products like edamame. Also nuts.

they eat beans.