Two charities that address health and social inequalities announced today they plan to merge to form an organisation with 1,100 staff and income of more than £35m.
The merger is due to be completed by April and the new charity will adopt Humankind's name.
Both organisations, which are funded mainly by local authority contracts, said the merger would not lead to job losses.
Humankind, which was founded in 1984 and known as DISC until it rebranded this year, has increased its income from £16.1m in 2014 to £26.2m this year, according to accounts filed with the Charity Commission.
Based in Newton Aycliffe, County Durham, it provides a wide range of services, including substance use, employment training and housing support.
Income at Blenheim CDP, which mainly provides drug and alcohol services, declined to £9.2m last year from £10.2m in 2016, according to its accounts.
Blenheim CDP's current funders include Kensington & Chelsea Council in London as part of the response to the Grenfell Tower fire, which killed 72 people.
Paul Townsley, who has led Humankind for more than three years, will become chief executive of the merged organisation.
John Jolly, chief executive of Blenheim CDP, will adopt the new position of executive director of external affairs.
Jim Black, chair of Humankind, will become chair of the new, single board. Eric Feltin, chair of Blenheim CDP, will become vice-chair.
Townsley told Third Sector that, although Humankind had more income, it was a merger of equals among two successful charities. He said both charities would retain their offices.
He said staff and stakeholder reaction to the merger, which is awaiting final sign-off by the boards, had been "really positive".
Townsley added: "As two separate organisations, we have worked successfully across both the north and south of England for the past 50 years.
"We believe it is now time to come together to create one organisation that takes a new approach to addressing health and social inequalities."
Jolly said: "Our decision to merge has resulted from our shared desire to pursue our objectives, increase our impact and grow the services we offer."
He added that Blenheim CDP services would keep its name and branding.