By Mark Easton
Home editor, BBC News
It is an uncomfortable conclusion from happiness research data perhaps - but multicultural communities tend to be less trusting and less happy.
Research by the Home Office suggests that the more ethnically diverse an area is, the less people are likely to trust each other.
The Commission for Racial Equality has also done work looking at the effect of diversity on well-being.
Interviewed on The Happiness Formula, the chair of the Commission for Racial Equality, Trevor Phillips accepts that people are happier if they are with people like themselves.
"We've done work here which shows that people, frankly, when there aren't other pressures, like to live within a comfort zone which is defined by racial sameness.
"People feel happier if they're with people who are like themselves. But the question is: what does "like themselves" mean?"
Tapestry of life
To an extent, new immigrants are always seen as outsiders and threatening. It is not necessarily a matter of ethnicity.
The arrival of the Huguenots or the Jews into Britain brought significant social tensions which have largely disappeared.
Cultural difference eventually became woven into the tapestry of British life.
Globalisation has brought new challenges - a diversity of culture and ethnicity never seen before.
There have been fierce arguments as to whether social well-being is enhanced by celebrating difference or encouraging integration, even assimilation.
Trevor Phillips believes the debate has become dangerously confused.
"Our multiculturalism which started out as a straightforward recognition of diversity became a sort of system which prized racial and ethnic difference above all other values and there lies the problem."
So, if we want happy, stable communities, where should the balance lie between diversity and integration?
Trevor Phillips believes getting it right is vital: "We need to respect people's ethnicity but also give them, at some point in the week, an opportunity to meet and want to be with people with whom they have something in common that isn't defined by their ethnicity."
"If we can find a moment, an idea, an activity which takes us out of our ethnicity and connects us to other people of different ethnicities and if only for an hour in a week then I think we can crack this problem."
Social science is also trying to help make sense of the challenges.
In the jargon, they refer to the factors that bind similar people together in groups as "bonding social capital".
But it is argued that happy societies also need what they call "bridging social capital" - strong links between different groups.
"A society that has only bonding social capital and no bridging social capital looks like Beirut or Belfast or Bosnia, that is tight communities but isolated from one another."
The Lozells area of Birmingham has witnessed inter-ethnic conflicts
So says Harvard professor Robert Putnam, author of "Bowling Alone: The Collapse and Revival of American Community".
He argues that working out how to grow bridging capital is the great challenge for Western society.
"This is the crux of the problem. The kind of social capital that is most important for the success of a modern, pluralist, multicultural democracy - the bridging social capital - is the kind that's hardest to build.
"Therefore we've got to go about the task of creating new opportunities for people to make connections to people different from them.
When bonding social capital drowns bridging social capital, conflict is inevitable.
Trevor Phillips believes we saw it all too clearly in the disturbances in the Lozells area of Birmingham in the Summer of 2005.
A tight-knit Asian community came into conflict with a tight-knit black community because, Phillips argues, the ethnicity that binds each community together is stronger than the links between them.
"You have two communities who more or less faced each other across a single road. They are communities which have high levels of internal bonding.
"But actually there wasn't and is very little bridging between these two communities and I think this is a perfect demonstration of what happens when people who are very different, look very different and think they are very different never touch, never interact."
What is required is a sense of identity that overarches creed, culture or ethnic background.
Nation states take different views on how this might best be achieved. The French model is to have a strict definition of Frenchness that, for instance, prohibits religious head-scarves in schools.
In the UK, citizenship ceremonies for new arrivals and lessons in schools are built around the ideas of shared values including an understanding of and respect for our democratic institutions.
Among those values is a tolerance of diversity and cultural difference.
But it is, perhaps, in sport that the efforts to build bridging social capital are most obvious.
Whether it be two football teams from different local communities breaking down barriers or an Olympic squad reflecting the multi-racial reality of modern Western society, competitive sport is seen as an important tool in binding together diverse nations and making people happy.
Mark Easton presents The Happiness Formula which is broadcast on Wednesdays at 1900BST on BBC Two