On-ramping is the process of re-entering the workforce after taking a career break (usually to care for family). It is paired with the term "off-ramping", or exiting the workforce as a temporary career break.
The Hidden Brain Drain, a taskforce led by economist Sylvia Ann Hewlett, defined the term as "many professional women in the US do not drop out of their careers altogether, but they do take breaks. However, they often find it difficult to re-enter the workforce. This has been called 'off-ramping' (taking time out of a career for one reason or another) and 'on-ramping' (rejoining the career path). Women in the US, on average, spend a relatively short amount of time off-ramped (around 2.2 years), but even this can incur financial penalties. Women who spend around three years off-ramp see their earning power decrease by 37 per cent."  A study by the Center for Work-Life Policy found that more than 90 percent of those women who off-ramp eventually wish to on-ramp back into the work force. 
The term appears as early as 2005, reaching public mention on NPR  that same year. The term appears in articles in publications such as the Wall Street Journal  by 2006, and by 2008 appears in formal training materials for organizations such as the American Institute of Certified Public Accountants  as a business best practice.
Sylvia Ann Hewlett, as the likeliest originator of the term (in Hewlett & Luce (2005),) has developed a career site (YourOnRamp) to capitalize on it and is a supporter of the entrepreneurial networking organization LadiesWhoLaunch.
- Elaine Aarons, Hidden Brain Drain Taskforce, as reported in http://www.thelawyer.com/cgi-bin/item.cgi?id=114645&d=pndpr&h=pnhpr&f=pnfpr
- Hannah Seligson (2008-12-06). "Off Ramp to On Ramp: It Can Be a Hard Journey". NY Times. Retrieved 2012-07-25.
- "We Can Stop the Female Brain Drain," by Sylvia Ann Hewlett, March 6, 2005
- Sue Shellenbarger of the Wall Street Journal writes about the efforts of Lehman Bros and other Employers to help high achieving women reenter the workforce.
- "Off Ramp and OnRampers" (PDF) (Press release). Center for Work Life Policy. 2005-02-25. Retrieved 2006-07-03.