Maryland Law requires the Board of Education of Harford County to engage in a labor negotiation process called collective bargaining. In collective bargaining the Board formally negotiates labor contracts with employee associations of unions, which are referred to as bargaining units in Harford County. State law mandates that these labor contracts include such items as employee work hours, salary, healthcare benefits, and working conditions. A negotiated contract must be ratified by both the Board and the employee members of the unit. The labor contract, which is called a Negotiated Agreement, is kept in place for a set period of time and is binding.

The Board of Education negotiates with five bargaining units that represent all employees within the Harford County Public School system:

The American Federation of State, County and Municipal Employees (AFSCME) is the exclusive public school employee organization for all school custodians, facilities and maintenance trades workers, bus drivers, bus attendants, school cafeteria workers and other non-instructional support related employees. AFSCME represents approximately 720 employees of Harford County Public Schools.

The Association of Harford County Administrative, Technical and Supervisory Professionals (AHCATSP) is the exclusive public school employee organization for all non-certified supervisors. This includes department managers, supervisors, computer programmers and analysts, coordinators and other related non-certificated supervisory personnel, school nurses, purchasing agents and specialists. AHCATSP represents approximately 180 employees of Harford County Public Schools.

The Association of Public School Administrators and Supervisors of Harford County (APSASHC) is the exclusive public school employee organization for the certificated administrators and supervisors. This includes principals, curriculum supervisors, instructional coordinators, assistant principals, instructional facilitators, pupil personnel workers and other related certificated supervisory personnel. APSASHC represents approximately 200 employees of Harford County Public Schools.

The Harford County Education Association (HCEA) is the exclusive public school employee organization for all teachers, guidance counselors, psychologists, media specialists, occupational therapists, physical therapists, and speech and hearing clinicians. HCEA represents approximately 3,200 employees of Harford County Public Schools.

The Harford County Education Association is the exclusive public school employee organization for all clerical/secretaries, paraeducators, team nurses, instructionally-related technicians, school bus driver instructors, transportation specialists, transliterators, sign language interpreters, Braille technicians, inclusion helpers, and related instructional support personnel who work twenty (20) or more hours per week. HCEA (ESP) represents approximately 1,100 employees of Harford County Public Schools.