This paper presents and discusses a research applied to an industrial group in Altamira, Mexico, and the inception of a labor productivity improvement program for the construction and maintenance of Aguila Industrial Group. The research focuses on the development of a methodology to assess the labor productivity of industrial maintenance projects. In the methodology we propose the work sampling tool in order to identify the main factors that affect labor productivity. We also propose applying lean thinking to improve labor productivity. The construction and maintenance industry is one of the areas that present a lower degree of development in most Latin-American countries, with which it becomes an activity which is characterized by great deficiencies and lack of effectiveness. However, the need for improvement due to constant change of scenarios where the activity develops has been detected.