Furnishing ones goals with implementation intentions (i.e. ''If I encounter situation X, then I'll perform behavior Y'') has been shown to be an effective self-regulatory strategy to improve goal-achievement.Recent research has suggested that the beneficial effect of implementation intentions on goal-success can be moderated by situational and individual factors. However, the results of this research were not fully conclusive.The studies presented in this work are intended to further investigate the moderation of the implementation intention effect by exploring three different factors, which are assumed to impair the efficiency of the if-then-plans.Two of the three factors were indeed found to moderate the effect of implementation intentions on goal-achievement. The third study failed to show the expected result due to methodolgical issues. The importance of these findings for laboratory and field studies using implementation intentions is discussed and implications for future research are presented.