Between 1997 and 2002, Hidalgo worked as a staffer in three ministerial offices within the government of Lionel Jospin: first in the office of Martine Aubry at the Ministry of Employment and Solidarity as technical advisor; then with Nicole Péry, Secretary of State for Women's Rights and Vocational Training, from 1998 to 2000, as technical advisor then consultant to the firm, participating, in particular, in the drafting of laws on parity and professional equality between women and men; and from November 2000 to May 2002, as a technical adviser and then mission manager, responsible for social relations and the status of civil servants, in the office of Marylise Lebranchu, Minister of Justice.