This paper shows how contingent valuation studies can produce relevant information for public nature conservation decisions. The study analyses the preferences of Finnish households for a nature conservation programme, Natura 2000 Network, by applying a dichotomous choice referendum model of the contingent valuation survey. In order to study the influence of attitudes and beliefs on a choice between the status quo and the new conservation project, an attitude-behaviour framework is applied. Beliefs concerning the outcomes of the nature conservation policy and evaluations of their importance describe how attitudes towards the programme are formed. The choices in the referendum are explained using a logit regression model and are found to be a function of attitude and socio-economic variables. The probability of a person supporting the proposed conservation level depends significantly on the income, age and background (urban-rural) of the respondent. The estimated model of choice behaviour is used to calculate the average willingness to pay for the Natura 2000 Network, which is also compared to the costs of the conservation programme.