To thrive as a Mainframe Developer with COBOL, you need expertise in COBOL programming, mainframe systems (such as IBM z/OS), JCL, and database management, typically supported by a degree in computer science or a related field. Familiarity with tools like TSO/ISPF, DB2, CICS, and source control systems is commonly required, and certifications in mainframe technologies can be advantageous. Strong problem-solving, attention to detail, and effective communication skills help you manage complex legacy systems and collaborate with cross-functional teams. These skills and qualifications are vital for maintaining, enhancing, and supporting critical business applications that rely on mainframe environments.