If you were born outside Canada, you were a Canadian citizen when you were born if, at that time, at least one of your parents was Canadian. However, if your Canadian parent was also born outside Canada (which would make you a second generation Canadian born abroad), you have to take steps to retain your citizenship before you turn 28. This rule applies if you were born on or after February 15, 1977, and if your parent born outside of Canada was also born on or after February 15, 1977, or was born before February 15, 1977, but the birth was not registered until after that date.
On April 17, 2009, the law will change to end the need to retain citizenship for many people. However, people born outside Canada who are subject to the retention rules and who turn 28 before the new law comes into effect must still take action to retain their citizenship.