The ecology of stream organisms varies with spatial scale and network context, but this has not been the focus of investigations on stream dwelling amphibians.  The tadpoles of Rocky Mountain tailed frogs (Ascaphus montanus) reside in headwater streams for three years and can comprise most of the vertebrate biomass in these systems.  We conducted extensive surveys of tadpole distribution by age class (1-3y), their food (periphyton), and physical habitat throughout two biogeoclimatically distinct networks in northern Idaho and northwest Montana.  To detect patterns across a hierarchy of spatial scales, we stratified each network into segments, reaches, and channel units, and randomly sampled 120 channel units in each, from headwaters to the largest stream order occupied by tadpoles.  In both networks, abundance of 1^st-year tadpoles increased from headwater to intermediate-sized reaches and decreased in larger reaches, whereas 3^rd-year tadpoles increased with stream size.  Tadpole density was highest in network areas where small streams were concentrated.  Although tadpole abundance was similar in the two networks, one network had more than 2-fold higher substrate embeddedness and periphyton biomass than the other.  The magnitude and sign of tadpole-habitat-periphyton associations changed accordingly, indicating factors limiting their distribution and abundance may vary with regional context.