Fonstad began her career at Bain & Company after spending a year teaching high school math in sub-Saharan Africa.[8] She joined venture capital firm Draper Fisher Jurvetson as a Kauffman Fellow in 1997 and became a partner in 1998.[9] Fonstad spent 17 years with DFJ, helping to grow the firm from $150MM to $3.5Billion under management.[10] Her investments included Athenahealth (ATHN), NanoString Technologies (NSTG), NetZero, Flurry, Lumenos, and others.[8]