This study examined the impact of the manipulated task complexity (Robinson 2001a, 2001b, 2007, 2011; Robinson & Gilabert, 2007) on second language (L2) speech comprehensibility. I examined whether manipulated task complexity (a) impacts L2 speech comprehensibility, (b) aligns with L2 speakers' perception of task difficulty (cognitive complexity), and (c) influences the use of different linguistic features that construct comprehensibility. Forty Korean undergraduates completed five tasks, differing in complexity, within a single task type (picture narrative). Students were also interviewed regarding task difficulty and how they identified the task in terms of cognitive complexity. Ten raters judged the participants' speech comprehensibility and linguistic features. The linguistic features of the participants' language productions were analyzed--individual speech variables were coded, and five degrees of task complexity were accounted for. The most complex task scored highest on comprehensibility, accentedness, fluency, and linguistic features (pronunciation, vocabulary, and grammar), whereas the least complex task scored lowest. Statistical analysis revealed that task complexity played a crucial role in comprehensibility and the use of a broad range of linguistic features. The findings point to task-specific, multifaceted relationships between comprehensibility and linguistic assessments.