Social Insurance Number (SIN)

A Social Insurance Number (SIN) is the Canadian equivalent of a Social Security Number (SSN) in the U.S. It takes about 3 weeks to get your card, and there is no charge for your first application. You need one in order to work.

I don't know if I have an SIN yet, so I will have to call them to find out what to do.

There is a toll-free number for callers inside Canada:

1 800 206-7218 option 3
Monday to Friday from 8:30 am to 4:30 pm (your local time), except statutory holidays

but if you call from abroad you have to call long-distance

(506) 548-7961
8:00am to 8:30pm (Atlantic time)

Here is where you can get the form to request a SIN:

http://www.hrdc-drhc.gc.ca/sin

Update 12/27/06:
I called and found out that if you come into one of their offices in person with your Canadian birth certificate, you will receive your SIN on the spot and then it takes about 10 days for you to get it in the mail. If I do it by mail, I was told, I may be separated from my original birth certificate for up to 8 weeks during processing. This is obviously something better taken care of after landing.