Kallos grew up in Manhattan and attended the State University of New York in Buffalo. He majored in psychology and communication and double-minored in philosophy and religion before going straight to law school.
After law school, he worked for Scott Stringer during his campaign for borough president. After being appointed to Community Board 8 in Manhattan, he became co-chair of the communications committee.
He also became a member of the Democratic Lawyers Council, where he worked as a regional coordinator for Sen. Kirsten Gillibrand during her 2006 run for Congress. Not long after, he signed on as chief of staff to Assembly Member Jonathan Bing.
While in that job, Kallos announced his candidacy for Jessica Lappin’s Council seat and opened a campaign committee as she was considering running for public advocate. When she opted for re-election, Kallos decided not to challenge her.
Despite that setback, the situation turned out well for Kallos.
He talked to several public advocate and Manhattan district attorney candidates before deciding which campaign to join. In the end, he says, Green inspired him most.