The inquiry, which is investigating claims of child abuse in Jersey's care system back to 1945, has heard evidence from 203 witnesses.
The next phase, in May, will hear from those who worked in children's services and those accused of abuse.
Chairman Frances Oldham thanked all those who had come forward and contributed to the work of the inquiry which started in 2014.
The now closed Haut de la Garenne children's home is among the island institutions at which accounts of abuse have been heard by the Independent Jersey Care Inquiry.
Ms Oldham said: "Whilst there have been some positive accounts, most of what we have heard has related to painful and damaging experiences.
"The first phase of the inquiry has been slow and painstaking, not least because of the difficulty many of the victims have had to wrestle with emotionally in terms of firstly giving a statement and then deciding whether to give evidence in public.
"We must establish the truth about how mistreatment of children remained hidden for so long and what was done when concerns were raised."
Chief Minister Ian Mr Gorst has set a deadline of December 2016 for the inquiry to conclude its investigations.
Jersey's child care inquiry has completed the first phase of evidence.