This article examines the question of teacher quality and its effects on the skills acquisition of primary school students in Spain. We use an education production function in which we incorporate teachers' fixed effects, estimated by means of a multiple regression model. Specifically, we examine the acquisition of reading skills by drawing on data from PIRLS-2011. The results obtained allow us to conclude that teachers constitute an important input in the acquisition of reading skills. Additionally, we analyse which observed teachers' characteristics can be related to teacher quality. By identifying the quality of each teacher in the sample, we are also able to determine where the "best" and "worst" teachers work. The results indicate that there is a greater probability of finding high quality teachers in privately owned schools and in schools where the students come from families with higher levels of economic and socio-cultural resources.