Based on the concept of map algebra, this research developed a network neighborhood analysis framework for directed flow networks. The analysis framework has two components: the first component defines how neighborhoods are delineated on networks and the second component calculates various statistics within the neighborhoods. The power and value of the analysis framework lie in its capability to delineate versatile network neighborhoods and its flexibility in calculating various statistics within the neighborhoods. It extends the raster map algebra to networks and provides a consistent analysis framework for the raster, vector, and network data models. Using a small section of the National Hydrography Dataset (NHD) networks, a prototype Web application is implemented to experiment and demonstrate the concept and uses of the analysis framework.