Golgi complexes (Golgi) play important roles in the development and function of neurons 1-3. Not only are Golgi present in the neuronal soma (somal Golgi), they also exist in the dendrites as Golgi outposts 4-7. Previous studies have shown that Golgi outposts serve as local microtubule-organizing centers 8 and secretory stations in dendrites <up>6, 9</up>. It is unknown whether the structure and function of Golgi outposts differ from those of somal Golgi. Here we show in Drosophila that, unlike somal Golgi, the biochemically distinct cis, medial, and trans compartments of Golgi are often disconnected in dendrites in vivo. The Golgi structural protein GM130 is responsible for connecting distinct Golgi compartments in soma and dendritic branch points, and the specific distribution of GM130 determines the compartmental organization of dendritic Golgi in dendritic shafts. We further show that compartmental organization regulates the role of Golgi in acentrosomal microtubule growth in dendrites and in dendritic branching. Our study provides insights into the structure and function of dendritic Golgi outposts as well as the regulation of compartmental organization of Golgi in general.