The Conservative Party has just published its EU Referendum Bill which would provide for a referendum before 31 December 2017.

The Question will be: “Do you think that the United Kingdom should remain a member of the European Union?”

 
Doesn't get more straightforward than that. It'll presumably be an In/Out referendum on the existing (reformed) terms when the vote takes place.

Some observations:

Some have suggested that the question is biased towards a "Yes", as it entails "think" rather than a simple "should the UK..."

For the referendum to take place, there still would need to be a further vote in both Houses of Parliament after the next election (even if hypothetically, the Bill would pass in this Parliament). So the Bill could still be subject to future Coalition politics and Lords opposition. This is the relevant section: "An order under this section may not be made unless a draft of the order has been laid before, and approved by a resolution of, each House of Parliament"

It is far shorter than the only precedents, Labour's ill-fated 2004 Referendum Bill or the Conservatives' last Bill. This is because more issues are left to subordinate legislation. Either this Bill will need amending during its passage through Parliament or detailed legislation on issues such as election spending and BBC immpartiality will be required at some point.

To get this Bill through the Lords, either now or in the future, would require either a) majority (unlikely now as the Lords have a Lib Dem / Labour majority, but may look completely different after 2015 elections) b) a manifesto commitment to allow the Salisbury Convention to be invoked or c) time to use the Parliament Act. 

 
Curiously, we note that Gibraltarians have been excluded from voting in this referendum...