The NCS Trust said it currently works with more than 300 local delivery providers to deliver the programme - which has a target of engaging 300,000 young people by 2020.
Cabinet Office data published last year showed 57,609 young people participated in 2014, well below the 90,000 target set by the Prime Minister.
The NCS Trust said it wants to work with organisations that have a pre-existing relationship with young people and a "deep reach" into communities.
A series of pathfinder pilot programmes will be run alongside its main programme this autumn with the aim of "deepening the reach of NCS into all communities and testing innovative approaches to support NCS as it grows".
The NCS Trust said it expects between 50 and 500 young people to be taking part in each pathfinder programme, with young people taking part being recruited "from outside of mainstream schools and colleges".
Michael Lynas, chief executive of the NCS Trust, said there are "brilliant youth organisations" that the trust doesn't currently work with.
"We see these pathfinders as an opportunity for the programme to tap into the experience, reach, creativity and commitment of some new partners who haven't been involved in the programme so we can make sure every young person, whatever their circumstances, has the opportunity to experience a high-quality NCS programme," Lynas said.
"We want to use these pathfinders to test and learn innovative and more flexible ways of delivering our core outcomes, so we can take forward and expand partnerships that work in the years ahead."
The NCS Trust said it hopes to have youth organisations signed up by the end of August. Interested groups should contact email@example.com