Canadian Citizens or permanent residents can sponsor family members from abroad if they are:

1. Your spouse (even same sex), common-law or conjugal partner 16 years of age or older;
2. Your parents or grandparents;
3. Your dependent children, including adopted children;
4. Children under 18 years of age whom you intend to adopt;
5. Your brothers, sisters, nephews, nieces or grandchildren who are orphans; under the age of 18 and not married or in a common-law relationship; or
6. A relative of any age if you do not have an aunt, uncle or family member from the list above who you could sponsor or who is already a Canadian citizen, Indian (Aboriginal Canadian) or permanent resident.

A son or daughter is dependent when the child is:
1. Under the age of 22 and does not have a spouse or common-law partner;
2. A full-time student and is substantially dependent on a parent for financial support since before the age of 22, or since becoming a spouse or common-law partner (if this happened before age 22); or
3. Financially dependent on a parent since before the age of 22 because of a disability.

NOTE:
Sponsors must promise to support the relative or family member and their accompanying family members for a period of three to 10 years (depending on the person being sposored) to help them settle in Canada.
Except for spousal sponsor, there is 'Lower Income Cut Off' limit to be met before a sponsorship application can be processed:

Effective until December 31, 2007
1 person (the sponsor) $20,778
2 persons $25,867
3 persons $31,801
4 persons $38,610
5 persons $43,791
6 persons $49,389
7 persons $54,987
Each extra person, add $5,598

The province of Quebec sets their own LICO limits and criteria for sponsorship eligibility.