The doctrine of adverse possession presents a risk to forestland ownership because timber management is infrequent. In this study, the extent of adverse possession claims on forestland in the United States is examined through a set of 243 published legal cases, and the determinants of the case outcomes are analyzed by a multinomial logit model. Those cases are from 32 states and distributed over 200 years, with an average of 12 cases per decade. Adverse possession claimants win 44% of the cases. The regression analysis reveals that whether an adverse possessor has a defective title is the leading factor in determining the case outcomes, and the periods required by statutes tend to negatively impact the winning probability of adverse possessors. The empirical findings have implications for landowners to defend their titles or remove a cloud on titles and for legislators to revise relevant laws in the future.