The present paper investigates the lexical process of conversion of verbal participles into adjectives in Polish and English. While Bresnan (1995) treats all premodifying -ing and -ed elements in English as participles converted into adjectives (e.g. sent in the recently sent book), it is argued here (in agreement with Laczkó 2001) that some prenominal -ing and -ed forms in English should be regarded as verbal participles. The authoress shows that a similar situation obtains in Polish, where prenominal participle-looking elements are either verbal participles or departicipial adjectives derived through conversion (e.g. dokladnie zmielone mieso '(lit.) carefully minced meat' vs. mielone mieso 'minced meat'). Difficulties are highlighted in delineating borders between verbal participles, departicipial adjectives, and other deverbal adjectives. Formal properties of the process of participle-to-adjective conversion are briefly compared to the characteristics of other conversion processes.