This paper explores the effects on workers' employability of workplace development opportunities during employment as perceived by the workers themselves. Data was collected through a survey conducted in 2012 in Italy using a sample of 558 workers. The aim was to test the effects of participation in training courses, workplace learning opportunities and career development support on career development in 2013. Results show that the main predictors of subjective career success are related to the career development support provided by supervisors, including mentoring and career counselling, and workplace learning opportunities provided through processes of job enrichment, job enlargement and job rotation. By contrast, participation in training courses does not bring any significant effects. The study also reveals that employees' opportunities for increasing their employability in the workplace depend on a number of personal and occupational characteristics. The study reaches the conclusion that firms can play a significant role in enhancing the career success of an individual and that employability can been encouraged by a mix of on-the-job workplace development opportunities.