How long does it take to reach proficiency in English?

I am reminded of  Jeanne D’Arc’s last line in Bernard Shaw’s Joan of Arc:

‘How long, O Lord, how long?’

I was so happy to read that it can take up to 3-5 years to reach oral proficiency.    We want our ELLs to succeed in their regular classes.  In order to do so, some students may simply need more time.

Thank you to one of my mentors: Larry Ferlazzo.

On average, how long do your students remain in your ELL program?