Background: The arrival of a sibling is a major transition for the first child and may result in behavioral and emotional challenges. Parental knowledge and attitude play a crucial role in preparing the older child and minimizing sibling rivalry. Objectives: To assess the effectiveness of a self-instructional module on knowledge and attitude of parents regarding preparation of the first child for the arrival of a sibling. Methods: A pre-experimental one-group pre-test and post-test design was adopted among 100 parents at Pooja Nursing College, Bhandara, Maharashtra, from March 2024 to March 2025. Convenience sampling was used. Data were collected using a structured knowledge questionnaire and an attitude scale. A pre-test was conducted, followed by administration of the self-instructional module, and post-test data were collected after one week. Statistical analysis included descriptive and paired t-test for comparison. Results: In the pre-test, most parents had poor to average knowledge and neutral attitudes. Post-test findings showed significant improvement, with 68% achieving good knowledge and 63% demonstrating favorable attitudes. Paired t-test revealed a highly significant difference in mean knowledge and attitude scores (p Conclusion: The self-instructional module was effective in enhancing both knowledge and attitudes of parents, suggesting its potential utility in maternal and child health education programs to ease sibling transition.