Qualifications and selection criteria of supervisors largely depends on the employer. Usually you will not be asked for any specific qualifications to become a supervisor. Good standard of general education is essential. Your personal qualities like good communication skills, responsibility and leadership will make your job sure. You should be having enough experience to become a team leader from a supervisor. Business mind, organisational and management skills are more important than academic qualifications. You should undergo continuous improvement through job training programmes. It is advisable to earn certified qualifications in management. It is helpful to pursue certificate courses of Institute of Leadership and Management (ILM) like Level 2 Certificate in Team Leading, Level 3 Certificate in First Line Management or Level 5 Diploma in Management while working with call centres, hospitals and retail industry. There certain equivalent qualifications provided by Chartered Management Institute (CMI).