Do step-parents have custody rights?

Not in general; courts tend to favor the natural parents. However, in extreme cases, step-parents can gain some custodial rights if the step-parent was very active in raising the step-child and the step-parent treats that child as his or her own. The most common situation in which a step-parent is awarded custody, however, is if the step-parent has custody of the step-child’s sibling and it’s best to leave the siblings together or if the natural parent is unfit.