Corporate Social Responsibility can be defined as a concept whereby businesses willingly integrate social, environmental and ethical standards into their operations in order to improve the organisation’s performance, lives of employees, local communities and the society as a whole. The study focused on determining the effect of Corporate Social Responsibility in the telecommunication sector: a case of Zamtel Limited. Previous studies have mainly focused on investigating the relationship between Corporate Social Responsibility and the company’s financial performance. Very little information is available on the concept with regard to the reasons why companies in the mobile telecommunication industry are engaging in Corporate Social Responsibility programmes. The researcher used a descriptive research design. Simple random sampling and purposive sampling methods were used to select a sample which comprised managers, unionised employees and customers of Zamtel limited. Out of a sample of 145 participants, only 120 questionnaires were answered and returned. This represented an 85% response rate which was very satisfactory. Primary data was collected through a questionnaire which had both quantitative and some qualitative questions. The data was analysed using descriptive statistics and multiple regression analysis. The results of the study showed that the independent variables being; the economical, ethical, legal and philanthropic responsibilities had a relationship with the dependent variable which is the company performance. The conclusion of this study was based on the multiple linear regressions, which examined the cumulative effect of the independent variables on the dependent variable. The multiple linear regressions gave a multiple correlation coefficient of 0.979, which showed that the relationship between the four independent variables cumulatively on the dependent variable was very strong and positively correlated. This implied that by investing in Corporate Social Responsibilities, companies in the telecommunication sector will have improved performance owing to customer and employee loyalty among other reasons. The study recommends that Zamtel Ltd invests in its employees and increases the support to social causes.