A Blockleiter (block leader) was the lowest official of the NSDAP, responsible for the political supervision of a neighbourhood or (city) block and formed the link between the NSDAP and the general population. Also colloquially known as a Blockwart (block attendant or warden), he was charged with planning, spreading propaganda and developing an acceptance to the policies of the NSDAP among the households (typically 40 to 60) in his area. It was also the duty of the Blockleiter to spy on the population and report any anti-Nazi activities to the local office. This was helped by keeping files on each household. Other duties included allocating beds in homes for visiting NSDAP demonstrators, the collection of subscriptions and charitable donations especially for Winterhilfe and organising the clearing of rubble after air-raids. It is thought that there were nearly half a million Blockleiter.

Blockwart in colloquial German today is an insult word for an informer.