Recent developments in procedures for selecting nature reserves have emphasized the goal of representing the full range of conservation features (e.g. species, communities, land systems) in a region. Iterative selection algorithms have proved to be very efficient at this task, but until now have not taken criteria for reserve design or land suitability into account. A new interactive computer program, CODA (Conservation Options and Decisions Analysis), overcomes these limitations. CODA is conceptually simple, yet powerful. A broad range of conservation objectives can be met and alternative reserve configurations can be displayed and compared. In this paper we outline the CODA procedure and apply it to a demonstration reserve planning exercise in southeastern New South Wales, Australia. The cost of reserve design criteria and of representing conservation features to different extents is assessed in terms of the total reserve area required. We discuss the implications of our results for formulating conservation proposals, especially with regard to competing land uses.