The charity wants to raise media and public awareness of the disease and dispel myths that it is the same as 'brittle bone disease', which is congenital.
Recent research found a low level of understanding about the condition and the preventive measures people can take to reduce their risk.
Good Relations will help launch a report into public attitudes about the disease in September. It will encourage people to dance through its 'boogie for your bones' campaign due to run in October.
The charity wants to stress that weight-bearing exercise helps improve bone health.
'Many people think osteoporosis is a frail old woman's disease,' said Good Relations account director Kirstin Kaszubowska. But she said that while one in two women get osteoporosis, one in five men are also affected.
The agency won the account following a three-way shootout. It will work with the national charity until the end of December.
People under 30 will be targeted through consumer magazines and the web to make them aware of a range of preventive steps they can take to reduce their risk of disease. Research has shown that bone health deteriorates after the age of 30.
This week the charity launched a campaign to encourage people to regularly get 15 minutes of sun exposure.