Smith Commission: Advice body and housing group in plea over welfare
The group tasked with looking at new Holyrood powers has been told there should be "major discussions" about the future of welfare.
Margaret Lynch, head of Citizens Advice Scotland (CAS), said powers over welfare issues should be devolved.
That view was echoed by the Scottish Federation of Housing Associations.
The Smith Commission, set up after the referendum "No" vote, met at the Scottish Parliament where it heard from a number of civic groups.
All five of the political parties at Holyrood are represented on the commission, which split into two groups in a bid to hear a broader range of views.
Ms Lynch told BBC Radio Scotland's Good Morning Scotland programme: "Our position is that welfare and social security should be devolved.
"It is clear from the bulk of submissions to the Smith Commission already that most of them think we should be devolving all or part of welfare to Scotland."
By Craig Hutchison, BBC Scotland's Democracy Live
"Today's sitting of the Smith Commission is unusual in a number of ways.
"For the parliament, and indeed the BBC, to televise an event at Holyrood, run by an entity which is outside the Scottish Parliament, is rare indeed.
"For that evidence session to be so large that it requires two committee rooms is, in my experience, unheard of.
"Lord Smith has insisted he is determined that the voice of the public and Scotland's civic institutions will be heard and that is exactly what is happening."
Ahead of the parliament meeting, CAS sent a letter to the commission which said: "Alongside the major constitutional changes we may see over the coming months, we cannot forget that it is not speed that is of the essence but thought and discussion; time and perspective.
"It is robust and practical debate and consultation that is needed.
"As we have seen from the referendum debate in Scotland, the people have a voice they want to use, they have views they want aired and they have policies they want to debate.
"There was time and consideration given to the referendum debate - something that is lacking in the speed of which strengthening the powers of the Scottish Parliament through the Smith Commission is being carried out."
Mary Taylor, chief executive of the Scottish Federation of Housing Associations, said that Holyrood should get full powers over the social security system, apart from pensions.
She added: "Our case is to give the Scottish Parliament substantive and coherent new powers to be able to tackle poverty and inequality.
"In our submission to the commission, we argue that full powers over the social security system (excluding pensions) and of its financing are needed.
"We call on commission members to avoid any temptation to cherry-pick elements of the social security system."
"There are many complex interactions between the different welfare benefits, policies and tax allowances that pay for them, too many to separate some out on their own, and we need the Scottish Parliament to be able to exercise full control over the system to make change which will improve the lives of people living in poverty."
In the run-up to the independence ballot, UK political leaders David Cameron, Ed Miliband and Nick Clegg, all vowed that substantial new powers - including some responsibility for tax and welfare - would be transferred to Scotland if the country voted to stay part of the UK.
The commission has been established to draw up a "substantial and cohesive package of powers" in a bid to bring about a "durable but responsive democratic constitutional settlement which maintains Scotland's place in the UK".
Under the timetable already agreed for reform, an agreement on recommendations for which new powers should be transferred north has to be reached by the end of November, with draft legislation produced by the end of January 2015.
This will then be implemented by whichever party wins next year's general election.