The Inquiry into Historical Institutional Abuse Bill passed its final stage, on 11 December 2012.
The inquiry, which will be headed by retired High Court judge Sir Anthony Hart, will examine allegations of abuse at children's homes, care institutions and borstals between 1922 and 1995.
The original bill intended the inquiry to cover the period from 1945 to 1995, however an amendment with an earlier start date passed at the consideration stage.
Junior Minister Jonathan Bell said the bill was designed to find out fully what happened and what could or should have been done to prevent it.
He said the inquiry would look at a possible apology, whether a memorial should be erected, and redress for victims - whether financial or in the provision of services.