The 73rd Constitutional Amendment Act established a three-tier system of Panchayati Raj in India (except for states with a population below 20 lakh, which may opt for a two-tier system). The three tiers are: 1. Village level: Gram Panchayat 2. Block level: Panchayat Samiti (also known by various names like Block Panchayat) 3. District level: Zila Parishad The Panchayat Samiti is the middle tier operating at the block level.