I've been with my boyfriend 14 years. We recently broke up 7/24/2012. He accepted my daughter as his own though she's not his biological child. He gave her his last name when she was about 4 year old. She's now 14 yrs of age. He's the only father she has ever known. Can I take him to child support in the State of NY?

Firstly-he cannot "give" her his last name. You can.
Secondly-did he sign Paternity acknowledgment ? Or promised IN WRITTEN that he is responsible for your daughter?
The doctrine of Equitable Estoppel may be used only in those cases.
What about child support from the biological father?

Her biological father has never been in her life. My boyfriend has been in her life since she was 1 month old. She calls him daddy and to everyone she is his daughter. We live together for 14 yrs. When she was born she had my last name, when she turned 4 yrs old he signed the birth certificate because he wanted her to have his last name being that he has been the only man she knows as daddy. Though she knows the truth she does not want to ever meet her biological father. (He wanted me to have an abortion and wants nothing to do with her plus I haven't seen him in 12yrs. My boyfriend did signed the birth certificate when her last name was changed to his. I have the papers with his signature that they send me back with the new birth certificate.

... Can I take him to child support in the State of NY??


.... My boyfriend did signed the birth certificate when her last name was changed to his. I have the papers with his signature that they send me back with the new birth certificate.

Probably. If he signed an affidavit of paternity, he is going to be hard-pressed to claim that he shouldn't be liable for CS because he committted perjury.

when she turned 4 yrs old he signed the birth certificate because he wanted her to have his last name being that he has been the only man she knows as daddy. ... My boyfriend did signed the birth certificate when her last name was changed to his. I have the papers with his signature that they send me back with the new birth certificate.

This is not the way it should work. Essentially you committed a fraud by attesting that he was the father.

But, on the other hand, I think a court would maintain that he is the legal father. So yes, file for child support. If he fights it on the grounds that he is not the legal father, you can show he signed the birth certificate and has treated her as his daughter since then.