Assessment is a vital aspect of curriculum practice. The study adopted explanatory mixed-method approach and sequential research design. The population for the study comprised all Social Studies teachers in Junior High Schools in the Ayensuano District. Convenient sampling techniques and census method were used to select the district, and all the one hundred and twenty-seven (127) teachers who teach Social Studies in the junior high schools in the district. The main instruments used for data collection and analysis were questionnaire and interview guide. The quantitative data was analysed both descriptive and inferential statistical tools. The qualitative data was transliterated and coded based on themes. Pre-set themes were used to generate the transcript (text) data based upon the research questions and discussed. The study concluded that authentic assessment practices by Social Studies teachers included the occasional guidance they give to their students about how to interpret topics and situations into relevant tasks with a clearly defined goal, and how to relate their knowledge in practical challenges. The study also revealed that refined essays, oral presentations, interviews, case study discussions, and live performances as authentic assessment strategies or tools Social Studies teachers used in assessing their students' learning outcomes in lessons. The study indicated that large class size, traditional assessment (examination) system, insufficient logistics and infrastructure, a paucity of funds to begin various activities and programs, a lack of motivation from school administrators, time constraints and difficulty in developing some authentic assessment tasks coupled with assessing some lessons using authentic assessment method are some of the criteria that influence the effectiveness of authentic assessment execution in teaching Social Studies courses. It is recommended that educational leaders should provide the resources to motivate Social Studies teachers to use authentic assessments for students’ learning in the classroom situation. It is also recommended that, Colleges of Education, Universities and National Teaching Council should organise professional development workshops and seminars to build the capacity of trained Social Studies teachers on the effective uses of authentic assessment practices.