Adopting a quasi-experimental design with four points in measurement, this study developed and tested a model whose variables represented key elements of the sustainable career process as captured in up-to-date thinking. The model posited that employees' openness to experience and supervisor support for training would lead to increases in employees' job performance and employability via learning as the result of an employer-sponsored training course. Training represented the contribution of the employer, who is the other key stakeholder in sustainable careers. The model was tested on 334 salespersons who attended an in-house job training course. Job performance and employability, as assessed by line managers, increased substantially and significantly following the training with respect to their pre-training levels, and learning as a result of the training mediated the relationships of openness to experience and supervisor support with the increases in job performance and employability. Contrary to expectations of a positive synergy, a substitution effect was found between openness and supervisor support in fostering learning as result of training, and subsequently, increases in job performance and employability. The study provided a comprehensive albeit short-term picture of the sustainable careers process as conceptualized in the theoretical literature. In addition, it illustrated the effectiveness of job training in the enhancement of employability. The implications of the study for theory and further research on sustainable careers and employability are discussed.