Empirical research on the (mal-)adaptiveness of favorable self-perceptions, self-enhancement, and self-knowledge has typically applied a classical null-hypothesis testing approach and provided mixed and even contradictory findings. Using data from 5 studies (laboratory and field, total N = 2,823), we used an information-theoretic approach combined with Response Surface Analysis to provide the first competitive test of 6 popular hypotheses: that more favorable self-perceptions are adaptive versus maladaptive (Hypotheses 1 and 2: Positivity of self-view hypotheses), that higher levels of self-enhancement (i.e., a higher discrepancy of self-viewed and objectively assessed ability) are adaptive versus maladaptive (Hypotheses 3 and 4: Self-enhancement hypotheses), that accurate self-perceptions are adaptive (Hypothesis 5: Self-knowledge hypothesis), and that a slight degree of self-enhancement is adaptive (Hypothesis 6: Optimal margin hypothesis). We considered self-perceptions and objective ability measures in two content domains (reasoning ability, vocabulary knowledge) and investigated 6 indicators of intra- and interpersonal psychological adjustment. Results showed that most adjustment indicators were best predicted by the positivity of self-perceptions. There were some specific self-enhancement effects, and evidence generally spoke against the self-knowledge and optimal margin hypotheses. Our results highlight the need for comprehensive and simultaneous tests of competing hypotheses. Implications for the understanding of underlying processes are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).