Background: Psoriasis is a chronic autoimmune skin disease with long-term impairment. The nurses have a great responsibility to develop efficient educational programs to improve the psoriatic people's knowledge and self-care practices that enable to reduce severity and disability index. The study aimed to evaluate the effectiveness of the educational program on the psoriasis severity and disability index of people with psoriasis. Research design: a quasi-experimental quantitative non-equivalent control group design. Setting: the study was conducted at the outpatient clinics of Cairo Hospital for Dermatology and Venerology (Al Haud Almarsoud Hospital). Sampling: A purposive sample consisted of 226 people with psoriasis divided into two groups (control and study groups). Tools: Three tools were utilized, 1) interview questionnaires for assessing demographic data and disease history, Psoriasis Knowledge (PKQ), and self-care practices.2) Psoriasis area & severity index (PASI), 3) Psoriasis Disability Index (PDI). Results: After program implementation, the follow-up test showed a significant improvement in the study group in good and average knowledge score levels of 47.8% and 32.7% respectively and adequate self-care practices of 78.8% with statistical significance relation between both groups (p< 0.000**). Also, there was a statistically significant improvement in the PASI in the study group compared with the control group (p<.0.015*). Additionally, a significant reduction in the mean score of PDI of the study group to 8.75±6.21. Conclusion: The educational program detected a significant positive impact on the severity and disability index of people with disability through improvement in their knowledge and self-care practices. Recommendation: Educational programs should be continuously conducted for improving the psoriasis people's knowledge and self-care practices.