Galina "Red" Reznikov:
While we do not know what exactly got Red in prison, we do know she was involved with the Russian mafia.
Poussey was arrested for selling marijuana.
Yvonne "Vee" Parker:
Vee was arrested for running a drug ring as well as hiring someone to murder someone in the ring who ran a side business secretly.
She was arrested for stalking and attempted murder.
While it is unclear why she was arrested, one can assume that embezzlement and murder play a part.
She was arrested for food-stamp fraud.
She is in jail for murdering a child; she claimed she mistook the child for a deer while hunting.
She was arrested for "illegal political activism."
Suzanne "Crazy Eyes" Warren:
We do not know much of her backstory or why exactly she was arrested.
While the reason for arrest is not obvious, we do know Nicky was a former drug addict.
She was arrested for smuggling drug money.
Tiffany "Pennsatucky" Doggett:
She was arrested for shooting an abortion clinic worker after the worker made a remark about Pennsatucky's fifth abortion.
Dayanara "Daya" Diaz:
Her exact crime is unknown.
She was arrested for credit card fraud (she stole the credit card information because sex change surgery was too expensive) and her son turned her in because he was not accepting of her transgender identity.
She was arrested for being a drug smuggler in a cartel.
She was involved in a drug operation.
Miss Claudette Pelage:
She was imprisoned for beating a man to death.
Tasha "Taystee" Jefferson:
Taystee was involved in the drug ring ran by Vee and was arrested for dealing drugs.
"Black" Cindy Hayes:
She was an airport security guard, and often stole from travelers.
Miss Rosa Cisneros:
She was arrested for being a bank robber.
She was arrested after handcuffing herself to a flagpole at a nuclear test site.
Carrie "Big Boo" Black:
She was arrested for running a gambling ring as well as theft or fraud.
She was arrested for fraud and endangerment after selling fake drugs.
She was arrested for armed robbery.
Leanne was arrested for drug possession.
Gina was arrested for embezzlement.
While the cause of arrest is unknown, it is likely to be drug-related.