In the central Oregon Cascades, mafic volcanic edifices include both short-lived cinder cones and a spectrum of much larger, longer-lived volcanoes. We analyzed olivine-hosted melt inclusions from explosive eruptions from three of the larger edifices to compare crystallization, volatile contents, and storage depths to those of the shorter-lived cinder cones. The melt inclusions were sampled from calc-alkaline basalt to basaltic andesite tephra collected from Belknap, Mount Washington, and North Sister volcanoes. Olivine host compositions are Fo80–83, Fo79–82, and Fo74–81, respectively. These Fo values are lower than the published values for nearby cinder cones (mostly Fo83–85), indicating greater extents of differentiation beneath the longer-lived edifices. The H2O contents of melt inclusions from each of the three volcanoes form a continuous range of values from ≤0.5 to ~2.5 wt% H2O. Many of the inclusions contain a vapor bubble, and the bubbles are mostly in the range of 1.0–6 vol% of the inclusion. After correcting bubble-bearing inclusions for the amounts of CO2 lost to the bubbles, our data show that variable degassing and olivine crystallization occurred beneath the larger edifices over a wide range of depths from > 7 km (> 2–5 kbar) to as shallow as ~0.1 km (~10–30 bars). In contrast, olivine-hosted melt inclusions from nearby cinder cones record entrapment at > 4–5 km depth, with no evidence for shallow crystallization and storage (e.g. Ruscitto et al., 2010). Our results demonstrate that the longer-lived edifices develop a vertically extensive zone of storage and crystallization that extends from the middle to the upper crust and continues into the core of the edifice itself. Modeled primary magma compositions for Belknap, Mount Washington, and North Sister are similar to those from nearby cinder cones, indicating that shield volcanoes and nearby cinder cones are supplied by the same magma sources. The results demonstrate that the shield volcanoes have more complex, shallow magmatic plumbing systems than that of the cinder cones.