Landscape permeability, usually known as connectivity in landscape ecology, defines to what degree organisms are capable of moving through a landscape. It is an important functional aspect linking landscape structure to the dynamics of populations, when these are at least in part determined by emigration and immigration of individuals. Landscape permeability is thus most relevant in landscapes with fragmented habitat and where populations are organised as metapopulations. This chapter briefly reviews how the two paradigms "habitat fragmentation" and "metapopulation dynamics" are related, which main effects of habitat fragmentation on populations have been found, and how structural landscape elements such as edges, matrices, barriers and corridors may determine landscape permeability for dispersing individuals. We use an example from our own work on capercaillie (Tetrao urogallus; Aves; Tetraonidae) to illustrate how the commonly used static approach of relating spatial population patterns to landscape structure is limited by the lack of empirical data on how dispersal actually takes place, and how the problem may be mitigated by studying the result of the unknown dispersal by genetic methods. We then follow the development leading from static distribution models to dynamic, spatially explicit population models and conclude that validation lags behind the theoretical development, again as a matter of lack of data on dispersal, particularly for vagile, large-bodied animal species. The chapter is concluded with some management-related observations regarding the restoration of landscape connectivity by means of movement corridors.