The paper describes techniques for reducing the adjacent channel interference that could be caused to a wanted, in-channel, amplitude-modulated (AM) signal. The interference is that due to the detected modulation of the unwanted signal as well as by the beats between the sidebands and carriers of both signals. The techniques include those based upon extraction of one or both signal carriers and their replacement and/or elimination before subsequent detection. Important features of the extraction techniques are that more precise analysis of the resultant effects are possible and the replaced carriers are added rather than multiplied with the original signal; the latter feature leads to an acceptable performance being obtained even when no extraction can be carried out. Some very powerful reduction techniques emerge through extraction of the unwanted signal carrier, but it is concluded that this raises some economic and operating problems with respect to the receiver; except, perhaps, for specialised purposes.