Discrimination against women in the UK is "deeply ingrained", a government report has concluded.
Many women face "multiple" barriers to success, according to interim findings of the Women and Work Commission.
On average, women in full-time work earn 18% less than men, while the part-time gender pay gap is 40%.
The commission will now consider whether legislation and mandatory pay reviews are necessary to improve opportunities for women. 'Deeply ingrained'
The Women and Work Commission was set up by the government in September 2004.
Its final report will be published in the autumn.
"Discrimination and lesser opportunity for women are deeply ingrained in our society," the report said.
"Some women are succeeding, in well-respected and well-paid careers, and are managing to combine work and family life, difficult though it may be at times.
"Others find it difficult to enter work, perhaps because of their caring responsibilities or through facing multiple discrimination." Bottom rung
The Equal Pay Act 1970 gave an individual the right to the same contractual pay and benefits as a person of the opposite sex in the same employment. WOMEN AT WORK: KEY FACTS
- Between 1971 and 2004: Female employment rate rose from 42% to 70%
- Women make up only 32% of managers and senior officials
- 64% of public sector workers are women against 41% in the private sector
- Having two children reduces earnings by an average of 10% while three or more children cuts earnings by 15%
- The full-time gender pay gap is 18.4%
- The part-time gender pay gap is 40.3% Source: Women and Work Commission
Caring responsibilities, part-time working and occupational segregation are the three main issues still affecting women's pay, the report said.
"Many are stuck to the floor of low-paid jobs, often with limited hours, and with few development or training opportunities," the report said.
Women still dominate the 5 "c"s - cleaning, catering, caring, cashiering and clerical work.
Women are under-represented in managerial positions, making up only 32% of managers and senior officials.
Girls however outperform boys at school, with more girls than boys obtaining GCSE and A level passes at higher grades.
But the commission is concerned that girls and women may be put off going into professions, which are higher paid and dominated by men.
The commission said there was evidence that school children received limited advice about work placements in areas dominated by the other sex. BBC News