Social science research on disaster-affected communities uses social capital to explain a variety of post-disaster outcomes. A promising recent line of inquiry looks at how disasters generate new forms of social capital, and reinvigorate place-based social networks and place attachment. Using survey data collected from 407 Calgary residents affected by the catastrophic 2013 Southern Alberta Flood, as well as interview data from 40 residents, this article examines factors that contributed to residents’ expansion of their social networks during the disaster, and the impact of expanded social networks on residents’ post-disaster place attachment and civic engagement. Findings reveal that people most affected by the flood, i.e., those who experienced house flooding and longer evacuations, were most likely to make new contacts during the disaster and immediately after it. However, results also indicate that these new forms of social capital did not translate into greater place attachment, even though they did engender some post-flood civic engagement. Overall, inundation, evacuation, and displacement are predictive of lesser post-disaster place attachment. The article concludes by discussing the relevance of the findings for theory and disaster scholarship.