Decision-making responsibility refers to decision-making and access to information rights in relation to children of spouses who were married. This used to be referred to as Custody

Joint decision-making responsibility is presumed (VL v DL, 2006 ABCA 89). Joint decision-making responsibility should not be disturbed without good reason, such as an unwillingness to work together, prolonged absence of a parent, some severe illnesses, extreme violence, or drug abuse which prevents the parents from cooperating.

Guardianship also applies to unmarried parents or third parties who have those rights, however married parents are usually also guardians. Mothers are automatically guardians, because it is easy for the hospital to identify who gave birth to the child. Fathers are generally presumptively parents where they are listed on the birth certificate, married or living with the birth mother at the time of birth, or where he acknowledges that he is the father, where they are married after birth, have lived together for 12 consecutive months at birth or within 300 days before birth. A father is a generally a guardian where he acknowledges that he is a parent of the child, and has demonstrated an intention to assume the responsibility of a guardian. That intention can be demonstrated by:

1. being married to the other parent at the time of the birth of the child;
2. being the Adult Interdependent Partner of the other parent at or after birth;
3. entering into a signed, dated, and witnessed agreement between the parents to be a guardian of the child;
4. marrying the other parent after the birth;
5. living with the other parent for at least 12 consecutive months at birth;
6. being married to the other parent by a marriage that, within 300 days before the birth of the child, ended by death, a decree of nullity, or divorce;
7. voluntarily providing or offering to provide reasonable direct or indirect financial or other support, other than pursuant to a court order, for the birth mother or for the child during or after her pregnancy; or
8. any other circumstance that a court finds demonstrates the parent’s intention to assume the responsibility of a guardian in respect of the child.

Special rules apply to assisted human reproduction and surrogacy.

If there is a dispute or uncertainty about who is a parent, any person claiming to be a parent can apply for a Declaration of Parentage.

Courts may also authorize blood tests or DNA tests, although they cannot be performed without the consent of the person to be tested. If a person refuses, courts can choose whether to infer that they are a parent.

Guardians must:

1. Provide information to any other guardian relating to the exercise of their guardianship, at the request of that other guardian;
2. Use their best efforts to co‑operate with one another in exercising their guardianship;
3. Nurture the child’s physical, psychological and emotional development and to guide the child towards independent adulthood;
4. Ensure the child has the necessaries of life, including medical care, food, clothing and shelter.

When courts are determining how to allocate decision-making responsibility or guardianship, they must only consider what is in the Best Interests of the child.

Unless modified by law or court order, those with decision-making authority/guardianship have the right to:

1. Be informed of and consulted about and to make all significant decisions affecting the child in the exercise of the powers and responsibilities of guardianship;
2. Have sufficient contact with the child to carry out their powers and responsibilities;
3. Make day‑to‑day decisions affecting the child, including having the day‑to‑day care and control of the child and supervising the child’s daily activities;
4. Decide the child’s place of residence and to change the child’s place of residence (see Relocation);
5. Make decisions about the child’s education, including the nature, extent and place of education and any participation in extracurricular school activities;
6. Make decisions regarding the child’s cultural, linguistic, religious and spiritual upbringing and heritage;
7. Decide with whom the child is to live and with whom the child is to associate (usually where there is a genuine safety risk);
8. Decide whether the child should work and, if so, the nature and extent of the work, for whom the work is to be done and related matters;
9. Consent to medical, dental and other health‑related treatment for the child;
10. Grant or refuse consent where consent of a parent or guardian is required by law in any application, approval, action, proceeding or other matter;
11. Receive and respond to any notice that a parent or guardian is entitled or required by law to receive;
12. Subject to the Minors’ Property Act and the Public Trustee Act, to commence, defend, compromise or settle any legal proceedings relating to the child and to compromise or settle any proceedings taken against the child;
13. Appoint a person to act on behalf of the guardian in an emergency situation or where the guardian is temporarily absent because of illness or any other reason;
14. Receive from third parties health, education or other information that may significantly affect the child; and
15. Exercise any other powers reasonably necessary to carry out the responsibilities of guardianship.

These rights don't necessarily mean that each parent has a veto or that they each have to come to a decision. Rather, it usually means that they can apply to the court to decide who can make a specific decision. It is important that parents consult each other though, a repeated failure to consult the other parent may be relevant to the allocation parenting time and decision-making.

Guardians can reallocate their powers and responsibilities by agreement, can apply for court orders to set rules about decision-making, or can apply to review a guardian's significant decision, where the decision involves a serious risk to the health or safety of a child, or it is likely to have serious long-term consequences for the child

If a court has to review decisions made by a person with decision-making responsibility or guardianship, that court will only consider what is in the Best Interests of the child.

Guardians who are parents can appoint replacement guardians in their Will, or through a written, signed, dated, and witnessed document.

Courts can appoint a guardian if that person is a parent, or if that person is an adult who has care and control of a child for more than 6 months, unless ordered otherwise.

Courts can terminate guardianship where either the guardian consents to the termination, or "for reasons that appear to it to be sufficient, the court considers it necessary or desirable to do so."