Referential and causal inferences are key abilities for the development of reading comprehension. It is hence important to delineate children’s developmental patterns of these abilities to serve as indexes for predicting future reading comprehension achievement and providing diagnostic sources of comprehension difficulties. This study aims at examining the development and interactions of different forms of pronoun and causality during reading short texts for 2^nd, 3^rd, and 4^th grade students, and further comparing differences between good and poor comprehenders. The numbers of participants for each grade were 174, 249, and 219 respectively. Thirty-six short texts were constructed with each contained two sentences. The first sentence always mentioned two characters and the second sentence related to the first one by varying pronominal (zero versus overt pronoun) and causal relations (high versus low causality). An interrogative question appeared at the end of each text to probe readers’ comprehension. Participants sit in front of a personal computer and read the texts in a self-paced manner by pressing designated keys. This study was a 3x2x2 mixed design with grade as a between-subject factor (2^nd, 3^rd, & 4^th grade) and pronoun forms (zero versus overt pronoun) and causality (high versus low causality) as within-subject factors. The main dependent variable was the reading time of second/inference sentences. The results indicate that three-way interaction is not significant. Two-way interactions among three factors are all significant. Overall, the developmental pattern shows that, older the readers, shorter the reading time for inference sentences. All grades show a similar pattern for processing inference sentences. The effect of causality is always significant with shorter reading time for high than low causality text for both zero and overt pronoun conditions. Further analysis reveals that, for high causal relation texts, inference sentence reading time for zero pronoun condition is significantly shorter than that of overt pronoun condition. However, for low causal relation texts, there is no inference sentence reading time difference between zero pronoun and overt pronoun conditions among students across all grades. After selecting poor versus good comprehenders from 3^rd and 4^th grade, we further analyze their differences in reading inference sentences. Third grade good comprehenders process inference sentences faster than poor comprehenders but there is no reading time difference between good versus poor comprehenders for the 4^th grade students. To conclude, both good and poor comprehenders take less time in reading the high than the low causality texts, and less time for zero pronoun than overt pronoun texts. This study has demonstrated that the high causal relation texts for zero pronoun conditions will improve children´s resolution process, whether they have good or poor understanding of the text.