Detectives investigating historical allegations of child sexual exploitation have arrested 20 men.
West Yorkshire Police detained the suspects, aged between 28 and 43, during a series of pre-planned operations in Calderdale.
Officers swooped on the men between Tuesday and Thursday and are now carrying out searches at properties in Calderdale and Kirklees.
They are being held over allegations made by a woman who claimed she was sexually abused as a child between 2006 and 2009, predominantly in the Halifax area, police said.
Two suspects have been released on police bail, while the remaining 18 have been released under investigation pending further inquiries.
Detective inspector Allan Raw said: "This investigation forms part of West Yorkshire Police's commitment to the investigation of both current and non-recent sexual offences against children. These are abhorrent crimes that affect the most vulnerable in our society.
"Protecting children and ensuring that victims are put at the heart of everything we do and continues to be a top priority for the Force.
"We have specialist safeguarding units in each of our five policing districts, which include officers dedicated to dealing with both current and non-recent child sexual exploitation."
He added: "We would urge anyone who has been a victim of sexual abuse, no matter when it took place, to report it to the police.
"Please be assured that you will be listened to, taken seriously and supported by professionals with experience of dealing with these kind of offences."