Disenrollment from health plans purchased on Affordable Care Act (ACA) Marketplaces is frequent; little is known whether disenrollment from off-Marketplace plans is as common or about the experiences and consequences of disenrollment. Using longitudinal administrative data on 2017-2018 nongroup plan enrollment linked with survey data, we analyze plan disenrollment in one regional insurance carrier servicing three states. Overall, 71% of enrollees disenrolled from their 2017 plan. Disenrollment was associated with purchasing through an ACA Marketplace, the carrier making significant changes to an enrollee's plan benefit design, being healthier, being younger, and paying a higher premium for their 2017 plan in 2018. Experiencing financial burden or poor access to preferred providers was not associated with disenrollment. Most disenrollees (93.2%) enrolled in other coverage, often at a lower premium, but lacked confidence that they could afford needed care. These results can inform policy to support enrollees through coverage transitions and foster stability in the nongroup market.