In this research, I investigate precontact territorial behavior in the San Juan Islands, Washington andSan Nicolas Island, California. Drawing on economic defensibility models, I generate hypotheses for change over time in boundary defense and permeability in the context of Late Holocene climate and settlement pattern change. Defensive characteristics of archaeological sites and lithic procurement patterns should reflect increased boundary defense and smaller territories when resources are adequate to the needs of the community. Extra-local materials should increase in abundance during times of resource scarcity. For the San Juan Islands case study, data on visibility, elevation, and distance to lookouts do not indicate significant changes through time in site location consistent with changes in boundary defense. Dissimilarities between artifacts from the Watmough Bay site (45-SJ-280) on Lopez Island and and nearby beach cobble toolstone suggests lithic procurement beyond the local beach at 1600-1000 cal BP, consistent with predictions for minimal boundary defense due to resource scarcity at that time. I do not find increased use of nearby beach cobbles or slate at 600 cal BP-Contact during a period of predicted increased boundary defense. Data on the spatial and temporal distribution of extra-local materials are insufficient to evaluate hypotheses regarding boundary permeability. For the San Nicolas Island case study, data on elevation and distance to lookouts do not indicate significant changes through time in site location consistent with changes in boundary defense. For the lithic procurement study using data from Tule Creek Village (CA-SNI-25) Mound B and CA-SNI-106, I found few changes through time in material type or artifact dimensions at either site that would indicate shifts in cobble procurement locations. Increases in abundance of chert are correlated with increases in sample size. For both study areas, results indicate potential sample size issues that must be resolved to further investigate my predictions. People may have engaged in boundary defense at a larger scale than the village; community boundaries may have always been permeable to interactions between kin and friends. This study has implications for social complexity studies and research on human adaptations to resource abundance and scarcity.