The present invention provides, among other things, methods and compositions for treating chronic lung disorders, in particular, bronchopulmonary dysplasia (BPD). In some embodiments, a method according to the present invention includes administering to an individual who is suffering from or susceptible to BPD an effective amount of an anti-Flt-1 antibody, or antigen binding fragment thereof, such that at least one symptom or feature of BPD is reduced in intensity, severity, or frequency, or has delayed onset.