The significance of non-mandatory training is presently being acknowledged across the globe and currently its importance has been raised to a level near to that of compulsory training. However, research evidence indicates that if the training is non-mandatory, employees are generally reluctant to participate in training programs. Yet, a study of the current literature suggests there is no appropriate theoretical framework to predict and explain the motivational and inhibitory factors underlying employee participation in non-mandatory training. This paper addresses this lacuna, drawing from the Adult Learning theory, the Expectancy theory and the Perceived Organizational Support (POS) theory; it argues that the perception of a supportive environment in the organization, the fostering of employees’ dispositional characteristics, job involvement and career motivation, working together enhance employees’ intention to participate in the non-mandatory training programs. Building on this argument further, it is proposed that when the perceived benefit of training is stronger, its effect on employee dispositional characteristics, job involvement and career motivation pertaining to participation in non-mandatory training becomes stronger. Being one of the early attempts at theorizing on employees’ intention to participate in non-mandatory training, this paper hopes to provide an appropriate theoretical foundation for the empirical work in this field, while providing an insight for managers involved in non-mandatory training of employees.