Although small and medium enterprises (SMEs) play a crucial role in the Vietnamese economy, this sectorโs growth is hindered by low level of technology and innovation. This paper uses firm-level panel data to examine whether process innovation activities in SMEs are influenced by their industrial environments. It measures the effects that agglomeration, the geographic concentration of firms within the same locality, has on firmsโ total outputs and their propensity to introduce new technology. Using a logistic model with firm fixed-effects, I find that agglomeration decreases outputs of informal firms and the likelihood of new technology introduction in all firms. However, there are evidence of positive lagged effects of agglomeration on innovation and heterogeneous effects across industries