Some embodiments include transistors having a channel region under a gate, having a source/drain region laterally spaced from the channel region by an active region, and having one or more dielectric features extending through the active region in a configuration which precludes any straight-line lateral conductive path from the channel region to the source/drain region. The dielectric features may be spaced-apart islands in some configurations. The dielectric features may be multi-branched interlocking structures in some configurations.