The funding agency for grassroots sport is to triple the amount of money it invests in tackling inactivity.
In a new strategy, Sport England will spend £250m over four years as it targets the 28% of people who do less than 30 minutes of exercise per week.
There will be a shift in emphasis towards the least active groups: typically women, the disabled and those from low socio-economic backgrounds.
It will also dedicate funding to children from the age of five.
Previously, Sport England has focused on helping youngsters from the age of 14.
As part of its new strategy, it will invest up to £30m on a plan to increase the number of volunteers in grassroots sport.
The organisation is also looking to work with a broader ranger of partners, with less money going to national governing bodies (NGBs).
Jennie Price, Sport England chief executive, said: "In the next four years, we're going to dedicate more time, expertise and more than £250m to tackling inactivity.
"We will be the single largest national investor in projects for people to whom sport and physical activity is a distant thought, or not even on their radar."
Responding to Sport England's announcement, Clive Efford MP, Labour's Shadow Minister for Sport, said: "We have been calling for a long-term plan that empowers the people who deliver sport at the grassroots in our communities.
"This is a step in the right direction, but we will be watching to see if Sport England is capable of the reforming itself to oversee the sort of changes we need."
Barry Horne, chief executive for the English Federation of Disability Sport, added: "This new strategy signals a major step towards seeking equality.
"Disabled people are the least active of all the under-represented groups in sport. That gives you an indication of the level of challenge ahead and it cannot be a short-term fix."
Nick Pearson, the chief executive of parkrun, said: "This feels to me like a watershed moment. This long-awaited directional change in strategy will encourage organisations to focus in areas that we know make a difference.
"We particularly welcome the extra investment into volunteering, into tackling inactivity and focusing on the next generation through extending the scope of investment to include children from the age of five."
Sport England directs more than half of its £325m annual funding towards NGBs, with a focus on more traditional, formal sport.
But, last year, the government voiced its displeasure after data suggested the growth in participation that followed London's successful bid to stage the 2012 Olympics was stalling.
Almost six out of 10 adults were playing no sport in a typical week.
Sport England was asked to back successful projects run by charities and organisations, outside the traditional NGB structure.
The main beneficiaries are likely to be Access Sport, Greenhouse Sports, parkrun, Sported, StreetGames and Street League - not-for-profit bodies that have enjoyed success in getting young people more active.
The impact of these programmes will be gauged in a new way, with the much-maligned Active People Survey being replaced by Active Lives - a wider survey that will also measure activities such as dance, rambling and cycling to work.
The new strategy comes at a crucial time for sport policy.
Funding was protected in last year's comprehensive spending review, but community sport depends on money from local authorities.
With local government grant funding suffering a 24% cut, non-statutory leisure budgets are under increasing threat.