Do you have to give up your Canadian pension, if you are Canadian and get dual Citizenship/ Canadian and American Citizenship

Sorry, but this is not a US immigration question.

Your questions regarding pension benefits and your tax obligations in Canada should be discussed with an attorney licensed in Canada. This is a forum for US attorneys, so we cannot address issues of Canadian law. As to your tax obligations in the US, you should speak to a US tax attorney or CPA. I have changed the practice area to Tax so that a US tax attorney might be able to assist you with your US tax questions.

I can't speak to the Canadian aspect of this but as a US citizen, you are required to file US income tax returns on your worldwide income. There is a special Form that allows deferral of taxes on certain Canadian Pension plans, thus avoiding a large tax liability in any one year. Also please keep in mind that the Canadian Pension may need to be reported on the Foreign Bank Account Reporting Form.