The number of affordable rental homes fell slightly in Calderdale last year, figures show.
Across the country, social and affordable rented properties managed by councils and housing associations continue to represent less of the housing stock.
The campaign group Generation Rent says the trend is forcing families into "poor-quality" homes.
Ministry of Housing, Communities and Local Government data shows there were 14,070 social and affordable rentals in Calderdale in 2018, when the most recent count took place – seven homes for every 100 people.
This was down by less than one per cent from the previous year, when there were 14,150.
Nationally, social and affordable rented properties dipped slightly between 2017 and 2018, to 4 million, following year-on-year rises from 2015.
The MHCLG said this was because of a fall in local authority homes outweighing rising housing association stocks.
Growing home ownership and the rise of the private rental sector mean social and affordable rentals account for a smaller share of the homes in England, dropping from 20 per cent in 2001 to 17 per cent last year.
In Calderdale, by comparison, they account for 15 per cent.
Hannah Slater, policy and public affairs manager at Generation Rent, said: "A lack of social housing has pushed families and vulnerable people into private renting, where expensive rents eat up large shares of household income, often in return for insecure, poor-quality homes.
"One in four families with children are now private renting, even though high 'no-fault' eviction levels mean families are unable to put down roots in their homes and communities.
"We need an urgent, long-term plan for building social housing to provide tenants with affordable, secure homes that support their wellbeing."
Head of policy at the National Housing Federation, James Prestwich, said the Government needs to build 145,000 affordable homes each year, including 90,000 for social rent, to meet demand.
He added: “In 2010, the Government cut almost all funding for social housing – this has had a huge impact, with a steep fall in the number of affordable homes being built over the last decade.
"Meanwhile, rough sleeping has risen by 169 per cent, and the number of people in temporary accommodation has hit a 10-year high.
"Without enough social housing, this will only worsen as more and more families are left behind by the broken housing market."
Housing minister Kit Malthouse said: "Providing quality and fair social housing is an absolute priority for me and so is helping people access housing support when they need it.
"Since 2010 the number of homes for social and affordable rent has increased by 79,000 and we’re giving councils the tools they need to push on and deliver a new generation of social housing."