Welsh Labour leader Carwyn Jones has been reappointed as first minister after a deal with Plaid Cymru ended a week of deadlock in Cardiff Bay.
He will now start forming a minority government, after the Queen's approval.
But in a fiery Senedd session, Plaid leader Leanne Wood said her party would vote against Labour again if needed, accusing it of "bullying" behaviour.
UKIP's Neil Hamilton also sparked a row calling her and Lib Dem Kirsty Williams Mr Jones's "political concubines".
'Caution and humility'
The comments came after Mr Jones outlined his plans.
He told AMs there would be legislation on public health, additional learning needs and on smacking.
But he said legislation would not be brought forward in the first 100 days so that AMs could establish a new, more collaborative way of law-making.
The Welsh people wanted Labour to proceed with "caution and humility", he told the assembly.
Mr Jones added his government's priorities would reflect "the successful result for Welsh Labour in the May election, and subsequent discussions with the main opposition party, Plaid Cymru".
Labour's main aims include a "relentless focus on securing a successful and sustainable future for our steel industry", and Mr Jones pledged ministers would "campaign vociferously for a Remain vote" in June's EU referendum.
He said Labour would then bring forward "a new Public Health Bill, an Additional Learning Needs Bill, and we will take forward, on a cross-party basis, legislation that will remove the defence of reasonable chastisement [of children]" and "seek to amend the current Welsh language measure".
But Ms Wood issued a warning to Labour not to expect an easy ride over the next five years after Plaid became the official opposition.
"Today is not about coalition," she said. "Today's is a one off vote to allow Labour's nomination to go through.
"And if that party thinks their bullying last week will stop Plaid Cymru from voting in a similar way in the future to hold you to account, then think again."
Ms Wood also refused to apologise for challenging Mr Jones for the first minister post which led to a tied vote and deadlock,
"I'm not sorry for what happened last week and I will do it again if I have to make Labour realise they are running a minority government," she added.
Meanwhile, Welsh Conservative leader Andrew RT Davies urged Mr Jones to clarify where he stood on controversial plans for an M4 relief road around Newport, improving the NHS and reducing the number of local councils.
"We will from the benches here hold you to account, on each and every corner that you try and turn", Mr Davies said.
"But we will also seek to be constructive in the way we engage and debate on the points that need to be brought forward."
Analysis by Nick Servini, BBC Wales political editor
Any suggestion that there would be a cosying up between Labour and Plaid came to an abrupt end when Leanne Wood wasted no time in laying into Carwyn Jones.
You would never have guessed that the two parties had been working closely together over the past few days on a deal when she described Labour as complacent, arrogant and having a sense of entitlement.
One AM described it to me after as being close to a declaration of war, and something that caused genuine surprise among Labour and Conservative ranks.
The inevitable question is how long the Labour-Plaid deal is likely to last in the light of Leanne Wood's tone.
Throw into the mix Neil Hamilton's description of Leanne Wood and Kirsty Williams as "concubines", and all round we were left with a spiky first session that kept us all guessing.