Purpose: Workplace learning (WL) is a key part of vocational education and training (VET) because it allows students to develop their skills in a work environment, and provides important information about how well VET studies prepare skilled workers. Therefore, the purpose of this paper is to develop and validate an instrument to evaluate WL efficacy in VET. Design/methodology/approach: The research presented in this paper was based on a quantitative design, after having identified factors that influence training efficacy. The factors to evaluate transfer in WL (FET-WL) questionnaire was formed of 57 items (five-point Likert scale) and applied to a stratified probabilistic sample of 1,026 VET students in the Barcelona area (Spain). Findings: After conducting an exploratory factor analysis, the model explained 48.42 per cent of the variance and six factors merged: coherence of the training of the school with the WL, school tutor's sole, host company tutor's role, the possibilities of developing the WL, integration into the company and student's motivation. Originality/value: Results show that the FET-WL may be a useful tool for the various agents involved in WL since it may improve the organization and management of VET and thereby increase its efficacy.