Cookies sold every year by Girl Scouts as a fundraiser. The earliest mention of the cookies comes from 1917, when a troop in Muskogee, Oklahoma baked and sold cookies as a service project. By 1922, the Girl Scouts were providing suggested recipes for Scouts in Chicago and suggesting they be sold for 25-30 cents per dozen.
The 1930s saw speedy developments in the Girl Scout Cookie concept. The first commercially-baked cookies were sold by Girl Scouts in Philadelphia in 1934, quickly followed by the Scouts in the Greater New York area in 1935 -- the New York Scouts had cookies baked in the shape of a trefoil and had "Girl Scout Cookies" printed on all the boxes. In 1936, the national Girl Scout organization started working to license their first commercial baker to make official Girl Scout Cookies, and by 1937, more than 125 Girl Scout councils were holding cookie sales.
Sales of cookies hit a bump during World War II when shortages of sugar, butter, and flour made it more economical to sell Girl Scout calendars instead, but the sales picked right back up, more popular than ever, after the war. In 1951, there were three varieties: sandwich cookies, shortbread, and chocolate mints; by 1956, the sandwich cookies had been split into vanilla creme and chocolate creme. Cookie sales expanded along with Girl Scout membership in the 1960s, and more cookie varieties, along with special packaging, were added -- all the packages were different depending on what part of the country you lived in, but in 1978, the national organization began providing the licensed bakers with standard cookie packages, so they'd all look the same.
Nowadays, Girl Scout Cookies come in eight different varieties (Thin Mints, peanut butter sandwich, and shortbread are mandatory for all the licensed bakers -- the others, including low-fat and sugar-free selections, are optional). All of them are kosher.
Research from http://www.girlscouts.org/about/cookie_hist.html