Decorative pictures, which make a learning text aesthetically appealing rather than provide information, have been predominantly found to impair learning by an increase of learning-irrelevant cognitive processes. Recent research, however, indicates that this effect is moderated by various factors. On the basis of cognitive–affective theories and studies, the affective charge and the degree of text–picture connectedness (i.e., the semantic relation of text and pictures) of decorative pictures reveal possible boundary conditions. To examine these design features and compare them with a group without pictures, 3 experiments (N1 = 108; N2 = 86; N3 = 162) with secondary school (Experiments 1 and 3) or university (Experiment 2) students were conducted. For this, decorative pictures consistent with those in instructional texts about South Korea (Experiments 1 and 2) or the human body (Experiment 3), were tested in a 2 (positively vs. negatively charged) × 2 (weakly vs. strongly connected to the text) between-subjects design with an additional control group. Learning performance, affective responses, and cognitive processes were measured. Results show that students with either positive or strongly connected pictures outperformed students with negative or weakly connected pictures. In comparison with the control group, strongly connected positive pictures enhanced learning and weakly connected negative pictures impaired learning. Although negative pictures were shown to increase task-irrelevant thoughts and extraneous cognitive load, weakly connected pictures increased the perception of intrinsic cognitive load.