Two common situations exist through which you can obtain custody of your children in the absence of a divorce proceeding, according to "Child Custody A to Z" by Guy J. White. You potentially gain custody absent a divorce proceeding through a voluntary agreement with your spouse, or as the result of an abuse and neglect proceeding directed at your spouse's fitness to parent, according to the American Bar Association Section of Family Law.
Voluntary Custody Agreement
Draft a written document through which your spouse assigns custody of the children to you. The document need not be complex. The provisions include a statement that your spouse is of a sound mind and that she desires to allow you custody of the children independent of her. Include information about why the custody arrangement is desired or required. For example, perhaps you and your spouse elected to embark on an informal separation due to marital problems.
Sign the custody document. Both you and your spouse execute the document, signing it in front of a notary public. You do not go to the courthouse to put the agreement into effect. You can go to court to seek enforcement of the terms of the agreement if your spouse does not comply.
Consider adding a termination date on the agreement. Absent such an agreement, the custody arrangement ends upon mutual agreement between you and your spouse or an order from the court.
Contact either a local law enforcement agency or child welfare agency in your county.
Advise the agency that you reasonably believe that your spouse is not fit to provide care for your children or that your spouse is guilty of abuse or neglect of the children.
Sign an affidavit provided by either the law enforcement authority; the state, county or district attorney; or the child welfare agency, attesting to the inability of your spouse to provide for your children or to the allegation of abuse or neglect.
Appear at the hearing scheduled by the court on the allegations. During this proceeding, the court considers the issue of custody of the children while an investigation occurs regarding the fitness of your spouse.
Request a custody order in your favor. Provided you are not implicated in mistreatment of your children, you are the likely candidate to gain custody of your children.