Poor essential workings in Mathematics is an attribute of poor problem solving processes. The study explored learners¿ problem solving processes in Calculus at 12 level. Calculus was introduced when the curriculum was revised in 2013 and involves basic differentiation and integration at this level. The study sought to establish Grade 12 learners¿ problem solving processes in Calculus, identify the challenges Grade 12 learners¿ encounter in solving Calculus problems, and determine strategies teachers and learners would suggest to improve problem solving-skills in Calculus. Twenty learners and two teachers at two secondary schools in Lusaka district of Lusaka province, Zambia, participated. A qualitative study approach, which followed a descriptive case study design was used. Data was collected using lesson observations, focus group discussions, and semi-structured interviews. Video and audiorecordings were used to capture observations and interviews, respectively, in their totality. Thematic analysis was used to analyse data. The four principles of problem solving by Polya namely, understanding the problem, devising a plan, executing the plan and looking back guided the analysis.