The Camino de Santiago is a Christian pilgrimage in the north of Spain leading to the city of Santiago de Compostela. For almost 1000 years pilgrims have walked hundreds of kilometers in the attempt to reach Santiago. Since the 1980's, there has been a resurgence of interest in the Camino, causing it to enjoy popularity unequaled since the Middle Ages. It has captured worldwide attention mainly due to the government's efforts to establish the north of Spain as a tourist attraction. Now, in addition to the thousands of pilgrims on foot or bike, there are millions of tourists who arrive in Santiago by charter bus or car. Surrounded by tourists, many pilgrims become obsessed with defining the authenticity of their journey and its difference from the tourist experiences. Using ethnographic methods of research, I walked 750 km of the Camino, followed by four weeks in Santiago de Compostela. I talked to locals and pilgrims about the convergence and divergence of tourism and pilgrimage and the need to define travel as authentic or inauthentic. I found that the investment in defining authenticity is directly correlated to a growth of government promotion of the Camino. As government promotion has increased, so has the number of people along the Camino and its integration into the mainstream of tourist destinations in Spain and Europe in general. As a result, its appeal is threatened because it relies on its status as markedly non-mainstream. I assert that the anthropological issue at stake is not what makes a pilgrim authentic or inauthentic, but why the authenticity of each pilgrim is so highly debatable.