Most bipolar models of affective processing in social psychology assume that positive and negative valent processes are represented along a single continuum that rangesfrom very positive to very negative. Recent research has raised the possibility, however, that the motivational systems for positive/approach and negative/defensive valent processing (positivity and negativity, respectively) are separable. In this article, the authors use unipolar positivity, negativity, and ambivalence ratings and bipolar valence, dominance, and arousal ratings of 472 slides from the International Affective Picture System to examine several aspects of the bivariate model of evaluative space. Analysis confirmed a positivity offset and negativity bias in the activation functions of the valent systems as wel as multiple modes of evaluative activation (e.g., reciprocal, uncoupled positivity, uncoupled negativity). Together, these data suggest that the bipolar structure of affective processes should be tested rather than assumed.