The Sustainable Development Goal (SDG) 4 stipulates Quality Education for all. The effectiveness of heads of departments (HoDs) contributes to achieving this goal. There is, however, a growing concern in recent times by stakeholders on the effectiveness of HoDs in discharging their duties. This study examined the administrative tasks performance of HoDs in Senior High Schools (SHSs) in Ghana. The study further examined the extent of professional development needs of HoDs in SHSs. A cross-sectional survey with a quantitative approach was employed. Through a multi-stage sampling technique, questionnaire was administered to 310 HoDs and 620 teachers in 155 selected Public SHSs.The study discovered that planning, organising, and controlling functions of HoDs were highly rated. However, supervision, evaluation, and directing functions of HoDs were rated low. It was further revealed that although HoDs were given professional training before they assume office as heads, they are rarely given any training after assuming office. The HoDs reported they greatly need professional development on management and communication skills, as well as training on assessment and evaluation competencies. HoDs need training on supervision, evaluation and directing function to be effective in the management of their respective departments. Unless frequent training programmes are organised for HoDs, the quality of education as well as the achievement of SDG 4 in Ghana would be jeopardised. It was suggested that together with HoDs, Ghana Education Service (GES) should regularly organise professional training programmes through workshops and seminars for HoDs in line with their duties as heads.