Bushey library was forced to close after a man reversed his car into the entrance following an argument inside.
Hertfordshire Constabulary were called at 3.14pm on Monday to the library in Sparrows Herne after reports of an altercation between a man and woman.
Between 3.05pm and 3.13pm the man, who was in the computer area, began shouting and swearing at the woman.
After punching the desk, he left the library slamming the door two or three times on his way out causing the glass to crack.
The man then got into his grey Vauxhall Astra and drove forward into the door.
After reversing, the offender then drove into the door for a second time breaking the door’s wooden frame and smashing the glass.
Police said he then drove off towards Watford.
Tom Shipp at Hertfordshire County Council confirmed the library was forced to close on Monday at around 4.15pm but reopened on Tuesday.
Police said the woman was left fearing for her safety and they are investigating the incident. No arrests have yet been made.