Nordman Christophe auteur aut IRD Wolff F.C. auteur aut IRD text journalArticle eng text/pdf reformatted digital access In this paper, we consider a model of on-the-job learning where workers learn informally by watching and imitating colleagues. We estimate the rate of knowledge diffusion inside the firm using two matched worker-firm data sets from Morocco and Senegal. We rely on non-linear least squares to estimate the structural parameters of the informal learning model and account for firm heterogeneity using firm factors derived from a principal component analysis. We find that the rate of knowledge diffusion is around 7 percent in Morocco and Senegal, but part of the learning-by-watching returns stems from firm heterogeneity. Informal training significantly affects the shape of returns to tenure in these two countries. Finally, we estimate an extended model with both learning-by-watching and learning-by-doing and find significant benefits from imitating colleagues in Morocco. specialized MAROC SENEGAL 100RETRA 096ENTRE 094CONSO 35 151-176 2012 1267-5059 https://www.documentation.ird.fr/hor/fdi:010087068 1267-5059 [F B010087068] https://www.documentation.ird.fr/hor/fdi:010087068 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2023-07/010087068.pdf IRD - Base Horizon / Pleins textes 2023-01-06 2023-07-26 fdi:010087068 fre