A native of Montana, Lake earned her Master's degree in Political Science and Survey Research from the University of Michigan at Ann Arbor. She attended Smith College as an undergraduate. Smith College awarded her its Distinguished Alumna Medal.

Lake has worked with organizations and individuals such as the AFL-CIO, the SEIU, Emily's List, The White House Project, Planned Parenthood, the Democratic National Committee (DNC), Arizona Governor Janet Napolitano, Senator Barbara Mikulski, Senator Debbie Stabenow, Senator Blanche Lincoln. She also served as a pollster to Martha Coakley, whose loss she credited to "the failure of the White House and Congress to confront Wall Street."

Lake focuses especially on women candidates and women's concerns. She co-authored a book, What Women Really Want with Republican pollster Kellyanne Conway.

Lake and her firm, Lake Research Partners, are known for their work on other issues including healthcare, education and the environment.