Switch on a radio phone-in, open your newspaper and you'll hear and read all about it - not least after the sweaty showdown between Farage and Clegg last night.
Everyone has an opinion, and nearly everyone has an experience to tell. And in a poll for Ipsos Mori this week, immigration and race has overtaken the economy as voters' top priority - with one in five seeing it as 'the most important issue facing Britain today'.
Whether you regard immigration as detrimental to Britain or key to its economic success often depends on your own personal experience of it.
This week on the Tonight programme, we try to unpack the truth behind the statistics, and behind the stories we hear in our towns and cities.
One bald fact: over the past 15 years Britain has seen its biggest-ever influx of immigrants - with more than half a million arriving in the last 12 months alone.
Visit Peterborough and it's obvious. It's the fastest growing city in England - with an extra 27,000 arriving since 2001, nearly all from Eastern Europe.
More than £500 million is being spent building hospitals and school buildings to cope with the numbers. One primary school we filmed at had a falling roll five years ago - now they have 180 on the waiting list, and 32 different languages are spoken there.
On a street a stone's throw away, the houses once occupied by white British families, have been bought up by developers to rent out to migrant families - changing forever the community living there.
But the leader of Peterborough's council - himself the son of Italian migrant workers - says immigration is good for his city, pointing out that people come here for opportunities often unrivalled elsewhere.
12,000 new jobs have been created here in the past three years - many in the booming agricultural sector in the farms and fields surrounding the city, supplying British produce for British supermarkets.
Some clearly feel the pain - but there's little doubt some also feel the gain brought by the immigrants who see our country as their best bet for a better life.
Tonight we hear from unemployed Brits who resent jobs going to foreigners; from managers who are building their businesses on the back of bright and energetic migrants; from a hospital dependent on nurses coming from abroad to care for all our needs; and from a councillor who mourns the loss of a community where everyone once knew their neighbour. And we take a cold hard look at the facts and the figures.
Tonight: The Truth About Immigration, 7.30pm on ITV and then on the ITV Player