In order to assess the effects of ambient contextual stimuli on retention, retro and proactive interference (RI and PI) seventeen experiments were conducted. In the retention experiments, the recall session was located in a context unlike the room used during original learning for one half of the subjects. In the inhibition experiments contextual changes were made between the usual three sessions of the RI and PI designs for the experimental groups. Retention decrements followed contextual changes when nonsense materials were used, but not when connected discourse or classroom materials were employed. When the second session (IL) in an RI experiment was located in a different context, improved retention resulted. In one PI experiment, a contextual effect was produced when session one (PL) was located in a different context but most of the PI experments did not produce interference when connected discourse or classroom materials were employed. (Author)