About 150,000 London council workers walked out in a pensions row closing a "large number" of schools and disrupting services, unions have said.
Four London refuse depots were closed, said unions
Boroughs hardest hit by the strike were Camden, Barnet, Waltham Forest, Southwark, Westminster and Bromley.
The Association of London Government said 22,000 workers walked out and a quarter (540) of all schools had shut.
Several unions are angry at government plans to scrap a rule allowing some to retire on a full pension at 60.
A Unison spokeswoman said action had led to the closure of a large number of London schools as well as libraries, housing departments and refuse depots in Lewisham, Southwark, Waltham Forest and Harrow.
The Local Government Association, which represents council employers, said workers in parts of inner London had shown "strong support" for industrial action.
The ALG said its figures gathered from London's town halls showed one in eight of the 178,000-strong workforce walked out, and said the impact had varied widely across the city.
Although teachers were not involved in the walkout, schools and some colleges were affected as many support staff including caretakers, cooks, cleaners and office workers joined the action.
Other workers supporting the strike included leisure centre workers, refuse collectors, housing officers, nursery nurses, youth and community staff and tourism officials.
The row is over the so-called Rule 85, which lets staff retire at 60 if their age, plus years worked, equals 85 or more.
The unions want workers who signed up for the scheme to have their pension rights protected, in the same way, they say, as uniformed police, NHS workers, civil servants and teachers.
The government said the rule must be replaced because women tend to join the workforce later and take career breaks, which makes the current regime discriminatory.
Eight trade unions - including Unison, the Transport and General Workers' Union and the GMB - voted to strike.