The Green Party is beginning its annual conference, with debates to include the state of the economy and care provision for the elderly.
During the four-day event in Hove, East Sussex, delegates will also discuss ways of reducing levels of teenage pregnancy and the war in Afghanistan.
There will be elections for the party's national executive.
The Greens gained 8.7% of the vote in Britain in June's European elections, up from 6.2% in 2004
Those attending the conference will be loaned free bicycles to get around Brighton and Hove.
Issues on the agenda include the future of the NHS, childcare provision, setting up a national rape hotline and protecting whistleblowers.
In her speech on Friday, party leader Caroline Lucas is expected to call for tougher regulation of City firms.
She is expected to say: "A paper recession forged in the international credit markets turned into a real recession affecting real companies, real job losses, real mortgage foreclosures.
"And meanwhile the banks continue to profit from an unjustifiable gap between base rate and the rate of interest they charge individuals and businesses, while the government does nothing except fail to regulate the way they said they would."
Deputy leader Adrian Ramsay is expected, in his speech on Saturday, to call for an end to private finance schemes within the National Health Service.
He is also expected to accuse Labour of "betraying the founding principles of the NHS through privatisation" and say the Conservatives "would be worse".
Ms Lucas, one of two British Green Euro MPs, is aiming to become a Westminster MP at the next general election.
She is running in the Brighton Pavilion seat, where the party took 20% of votes in 2005.
Delegates will take part in a "mass canvass and leaflet drop" in the constituency on Saturday.
The Greens currently have 123 councillors and two London Assembly members.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.