Grey Ranks (Polish: Szare Szeregi) was a codename for the underground paramilitary Polish Scouting Association (Związek Harcerstwa Polskiego) during World War II.

The wartime organisation was created on 27 September 1939, actively resisted and fought German occupation in Warsaw until 18 January 1945, and contributed to the resistance operations of the Polish Underground State. Some of its members (Grupy Szturmowe – Assault Groups) were among the Home Army's best-trained troops.^{[citation needed]}

Though formally independent, the Grey Ranks worked closely with the Government Delegation for Poland and Home Army Headquarters. The Grey Ranks had their own headquarters [pl] known under the cryptonym Pasieka (bee yard) staffed by the Chief Scout of Grey Ranks plus three to five deputies in the rank of Harcmistrz (Scoutmaster).

Since its organization in 1916, scouts from the Polish Scouting and Guiding Association (Związek Harcerstwa Polskiego (ZHP)) had taken an active part in all the conflicts Poland was engaged in around this time: Great Poland Uprising, Polish-Bolshevik War, Silesian Uprisings, and the Polish–Ukrainian War. After the German Invasion of Poland in 1939, the Nazis recognized the ZHP as a threat. Polish Scouts and Guides were branded as criminals and banned.

Under the leadership of Florian Marciniak, the ZHP carried on as a clandestine organization. The wartime Scouts evolved into the paramilitary Szare Szeregi (Grey Ranks), reporting up through the Polish underground state and the Home Army resistance organization.^{[citation needed]}

The codename Szare Szeregi was adopted in 1940. It was first used by underground scouting in Poznań. The name was coined after an early action of the Polish Scouting Association, in which boy scouts distributed propaganda leaflets among Germans from Lithuania, Latvia and Estonia who had settled in the homes of Poles expelled to the General Government. To create confusion, the leaflets had been signed SS — later expanded to Szare Szeregi, a name that came to be adopted by the entire organization.^{[citation needed]}

Older Scouts carried out sabotage, armed resistance, and assassinations. The Girl Guides formed auxiliary units working as nurses, liaisons and munition carriers. Younger Scouts were involved in so-called minor sabotage under the auspice of the Wawer organization, which included dropping leaflets or painting the kotwica sign on the walls. During Operation Tempest, and especially during the Warsaw Uprising, the Scouts participated in the fighting, and several Szare Szeregi units were some of the most effective in combat. The Grey Ranks also included the White Couriers, who, between late fall 1939 and mid-1940, helped smuggle many persons out of Soviet-occupied southeastern Poland into Hungary.^{[citation needed]}

In 1940, the Soviet Union executed most of the Boy Scouts held at Ostashkov prison.^{[citation needed]}