Headhunters should put forward at least one strongly recommended woman on shortlists for company directors, a report for the Government has recommended.
Business Secretary Vince Cable asked businesswoman Charlotte Sweeney to review a voluntary code followed by executive search firms under moves to increase the number of women on company boards.
The report makes a series of recommendations, including the creation of a database of "board-ready" women and guidance on the legality of women-only shortlists.
A review led by Lord Davies in 2011 set a target of achieving 25% of women in boardroom positions by 2015, with the current figure now just over 20%.
Mr Cable said: "The headhunting community is a crucial catalyst to introduce more capable women in the boardroom. However, they can often be one of the first hurdles that talented, board-ready women face when trying to reach the top, so I welcome any efforts to improve the transparency of the industry."
Ms Sweeney said: "Throughout my review, there was a clear, articulated commitment from the majority of search firms to support the creation of more diverse and balanced boards. However, examples where the commitment was transferring into consistent and sustainable action were mixed.
"Further transparency across the industry will help identify where any further barriers are and inform where focused action is required."