By Adrian Browne
Plaid leader Ieuan Wyn Jones has been deputy first minister for 14 months
Plaid will promise to "get on with the job" of delivering for people in Wales despite the tough economic times.
Plaid ministers will tell the party's autumn conference in Aberystwyth that the assembly government coalition with Labour is working well.
Key party figures will say Plaid is both creating a new agenda for Wales and winning people's trust.
Gordon Brown will be challenged to call a general election, with Plaid confident of getting more MPs elected.
Opening the conference, Rural Affairs Minister Elin Jones will say the party is the "dynamic and progressive force" in Welsh politics.
Ms Jones will assure delegates that Plaid's principles have not been compromised by being in government.
On Friday, party leader and Deputy First Minister Ieuan Wyn Jones will reject claims that a referendum on further assembly powers will not be held on or before the next assembly election in 2011.
Mr Jones is expected to say that if there is support for full law-making powers "then it should happen" and suggest that a "new confidence in Wales" could help the process.
Over the first 14 months of political marriage to Labour in Cardiff Bay, there have been some difficult moments along the way for the junior partner.
Although it lost control of Gwynedd Council in this year's local elections, Plaid is confident its record number of councillors, 206, demonstrates that being in coalition in Cardiff Bay is not damaging the party's identity.
Labour MP Don Touhig's intervention to claim that Plaid was "running rings around Labour" in the assembly government was also a bit of a morale boost from a surprise source.
A clear low point was the resignation of Plaid Culture Minister Rhodri Glyn Thomas over the summer.
He quit following claims he walked into a pub with a lit cigar, just weeks after announcing the wrong winner of the Wales Book of the Year
On Thursday his replacement, Alun Ffred Jones will outline his vision of the job, and attempt to allay concerns about progress of measures to strengthen the Welsh language.
He is expected to stress that his priority is to ensure that people are free to speak the language in their everyday life.
Despite the inevitable excitement about assembly matters, Plaid parliamentary leader, Elfyn Llywd, will warn the party not to take its eye off the Westminster ball.
He will say the team there is ready for a general election and confident it can increase its number of MPs.
Dafydd Iwan, re-elected party president after defeating Mr Llwyd, will explain how he hopes to get the party to expand its membership and embrace new technology, when he addresses the conference on Saturday.