This study expands the understanding of the role of informality in post-socialist professions by examining the use of informal practices by an under-researched professional group of engineers in Azerbaijan. We use in-depth interviews with engineers educated in Soviet and post-Soviet periods to trace changes and continuities in the use of informal practices in their education and work. The study found that although many practices inherited from the Soviet period (e.g. bribery in higher education and nepotism in employment) have undermined professional standards, others, such as reliance on interpersonal professional networks and reputations, have helped to transmit professional knowledge and preserve professional values. We argue that informality has a dual impact on the engineering profession in Azerbaijan: some informal practices undermine professionalism while others help to sustain it.