Two studies are presented in which favourable and unfavourable conditions for children's meta-cognitive monitoring processes are examined. Previously reported findings have shown that especially children's uncertainty monitoring (in contrast to certainty monitoring) poses specific problems for children in their elementary school years. When interviewing children about an observed event, answerable and unanswerable questions in two question formats (unbiased and misleading) were used, and 8- and 10-year-old children as well as adults were asked to rate their confidence on a three-point scale concerning each response. Results of Study 1 show that accuracy instructions and the option to answer with ‘I don't know’ inflate children's level of confidence because uncertain answers are withheld. Results of Study 2 revealed that children's difficulty with uncertainty monitoring may lie in a cognitive overload during the interview because immediate confidence judgments were less precise and less adequate compared with delayed confidence judgments. Participants' rating of their uncertainty after having erroneously provided an answer to an unanswerable question proved that children aged 8 years and older are able to experience and report levels of uncertainty but, as was shown for answerable questions, these emerging competencies are dependent on favourable task conditions.