The aim of this study is to investigate factors with both beneficial and harmful qualities for Cultural World Heritage Sites. Particular but not exclusive attention is given to aspects relating to tourism and infrastructure. Data from the World Heritage List for North America and Europe, linked to the 2014 UNESCO Periodic Report II, are employed for the analysis. A simultaneous Bivariate Probit model estimation is carried out on the 30,954 observations and 402 Heritage Sites. World Heritage managers assess that certain factors are both beneficial and harmful for their sites. These contradictory perceptions appear most commonly in relation to tourism/visitors/recreation (28% of the sites), ground transport infrastructure (16%) and to the Society's valuing of heritage (12%). Besides this, ambivalent perceptions are also identified for housing, commercial development, land conversion, forestry/timber production and renewable energy facilities, although to a lesser extent. Estimation results reveal that the highest degree of ambivalence occurs in relation to tourism/visitors/recreation, interpretive and sightseeing facilities and ground transport infrastructure when location and specific site characteristics are controlled for. Thus, the results coincide only to some extent with the descriptive statistics. Compared to other groups of Cultural World Heritage Sites (cultural landscapes, religious sites and other sites) managers of cities have a significantly lower probability of perceiving the different factors as harmful.