Progress in International Reading Literacy Study (PIRLS) was used to measure Indonesian fourth grade elementary school students’ reading comprehension in 2006 and 2011. Indonesian students scored among the lowest of the participating countries with a score of 405 in 2006 and 428 in 2011, with the PIRLS average scale score being 500. These results raised questions about the alignment of the Indonesian curriculum with PIRLS. Alignment research between the PIRLS 2021 frameworks and the Curr13 language standards and textbooks (the current Indonesian curriculum) was conducted to provide Kemendikbud (Indonesian Ministry of Education and Culture) with a prediction of students’ performance in future PIRLS. The alignment research was mixed methods research with an exploratory sequential design (a three-phase design). The first phase was qualitative data collection and analysis. Alignment instruments were developed using the components of Webb, NAEP ESSI, and HumRRO alignment models. The second phase identified features to be tested, where I revised the alignment instruments, guidelines, and codebook based on the first phase and created a new table. The revised instruments were then used to align Curr13 and PIRLS. The third phase was quantitative calculation using Webb's quantitative criteria (categorical concurrence, depth-of-knowledge consistency [DOK], range-of-knowledge correspondence, and balance of representation) and descriptive statistics. After the three phases, the interpretation used both the qualitative and quantitative data. The results found inconsistencies between Curr13 and PIRLS frameworks. There was no categorical concurrence between PIRLS frameworks and Curr13 unit assessments. Curr13 language standards and unit assessments did not include one PIRLS framework, evaluating and critiquing content and textual elements. This resulted in the absence of DOK for this framework. One PIRLS framework mostly covered by Curr13 language standards and unit assessments was interpreting and integrating ideas and information. DOK and balance of representation were achieved in this framework. Two PIRLS frameworks on comprehension processes (focusing on and retrieving explicitly stated information and making straightforward inferences) aligned to Curr13 and had a balance of representation but weak DOK. Meanwhile, Curr13 unit resources mostly aligned to one of two reading purposes in the PIRLS framework, acquiring and using information, but was weakly aligned with the other one, literary experience. The implication of research findings was to support Kemendikbud in predicting students’ performance in future PIRLS participation by examining the inconsistencies between Curr13 and PIRLS. Recommendations were provided for the elementary school teachers, students, parents, publishers, policymakers, local governments, and other elementary school stakeholders to be familiar with and understand PIRLS. The role of AKSI should also be maximized. In addition, the concept and practice of curriculum alignment should be introduced and enacted into the educational system in Indonesia.