Czechoslovakism (Czech: Čechoslovakismus, Slovak: Čechoslovakizmus) is a concept which underlines reciprocity of the Czechs and the Slovaks. It is best known as an ideology which holds that there is one Czechoslovak nation, though it might also appear as a political program of two nations living in one common state. The climax of Czechoslovakism fell on 1918-1938, when as a one-nation-theory it became the official political doctrine of Czechoslovakia; its best known representative was Tomáš Masaryk.[1] Today Czechoslovakism as political concept or ideology is almost defunct; its remnant is a general sentiment of cultural affinity, present among many Czechs and Slovaks.