Headwater streams, particularly those that flow only during part of the year, are understudied and underprotected in Massachusetts. Research being conducted elsewhere suggests that these "Headwater Habitat Streams" are important both for aquatic biodiversity and for ecological function of lower stream reaches. We are carrying out baseline research, involving research scientists and volunteers, on hydrology and habitat characteristics in headwater streams in northern Worcester County, MA. We hypothesized that headwater streams exhibit a longitudinal gradient of hydrology, from (1) ephemeral channels that flow only in response to storms, through (2) intermittent sections that flow seasonally until the groundwater table falls below the channel and are dry the rest of the year, to (3) interstitial reaches that flow seasonally and retain pools connected by subsurface flow during the summer, to (4) the perennial stream. Results to date show a high degree of longitudinal heterogeneity in the study streams, with interspersion of perennially flowing reaches among low-gradient sections of vegetated wetland, high-gradient boulder piles, and braided channels. Perennial flow is found high up in some watersheds. We expect our methods and results will have implications throughout the Commonwealth for local conservation commissions and other municipal officials responsible for land-use planning and regulation, state agencies responsible for land management and the protection of wildlife, regulators reviewing projects affecting streams, watershed managers, teachers and their students, private land trusts, conservation advocates, and citizen-naturalists.