Background: Access to employment for people with intellectual disability (ID) has become a social priority. The aim of the present study is to try to determine which variables [sociodemographic variables, intelligence quotient (IQ), presence or absence of a psychiatric disorder, functioning, self-determination, and behavioural problems] could most reliably account for access to remunerated employment of people with ID. Methods: Two groups of people with ID participated in this study: (1) 69 workers in a sheltered-employment programme; and (2) 110 clients of programmes in sheltered workshops. Both programmes were run by the Pardo-Valcarce Foundation in Madrid (Spain). The following variables were assessed for every participant: IQ, functioning, behavioural problems, self-determination and presence of psychiatric symptoms. A binary logistic regression analysis was carried out in order to identify the variables that best explained work outcome (sheltered workshop programme vs. sheltered employment programme). Results: Although IQ showed no significant differences between the two groups of participants, the remaining variables did: behavioural problems, functioning, psychiatric symptoms and self-determination significantly explained work outcome. As for sociodemographic variables, whereas gender did not show any significant relationship with the labour status of the participants, significant differences were found when considering variables such as age and pension benefits. Conclusions: All the main variables considered, except IQ, turned out to be significant. Our findings should be considered encouraging, as they apparently show that both personal and social efforts can help individuals to overcome their low intellectual functioning in order to achieve access to employment. Such study highlights the importance of a prior psychopathological evaluation and efforts to enhance self-determination in order to improve work inclusion for people with ID.