The inquiry by the public administration select committee of MPs will look at the costs and benefits of third sector service provision.
Tony Wright, Labour MP for Cannock Chase and chairman of the committee, said: "More and more of our traditional state services are now being performed by the voluntary sector. There are real issues that need discussion here."
The committee is asking charities for written evidence on the financial implications and benefits of charities delivering services. It will also look at contractual relationships.
The NCVO welcomed the inquiry, but said the sector required a full-time parliamentary body to scrutinise government policies on the voluntary sector. "The whole range of policies coming from government means there needs to be more parliamentary scrutiny than that," said Pete Moorey, parliamentary and media manager at the NCVO.
He added that a select committee dedicated to third sector affairs could also examine Charity Commission rulings.