Rounded Shoulder Posture (RSP) a.k.a Forward Shoulder Posture(FSP), is the usual maladaptive posture that alters the motions of the shoulder which may cause asymmetry in the shoulder and back muscles according to (Borstad & Ludewig, 2005, as cited in Jin, Jung, & Chul, 2014). Prolonged forward bending of the body, uplifting heavy objects, and habitual improper posture are some of the few causes of RSP (Wong, Lee & Yeung, 2009). According to the study of Jin, et., al, (2014), persistent trunk forward bending may establish the shoulders in a forward angle which tightens the pectoralis minor muscle that can result into RSP. These muscle maladaptation’s associated with RSP may contributes pain, limits a person’s physical movements and contributes in head and shoulder injuries. Increasing the length of tightened pectoralis minor muscle that pulls the scapula in an anterior position is an important component of RSP treatment. Hajihosseini et al. (2014) concluded that the “forward shoulder (FS) is one of the most common deformities accounted for 60% of shoulder abnormalities”. Therefore, clinical practitioners must address these anterior chest muscles maladaptation’s associated with RSP to prevent further injuries and disability. RSP correction and ideal proper posture can be attained by combining different therapies such as: “stretching and strengthening exercises, biofeedback training and behavior therapy”. (Hajibashi, Amiri, Sarrafzadeh, Maroufi & Jalaei, 2014). According to Wong, Coleman, Dipersia, Song and Wright (2009), mobilization of soft tissue, strengthening of the stretched muscles, and tightened anterior chest muscles stretching are ways of treating RSP. These maladaptation correction methods can regain normal shoulder joint movements and scapulohumeral rhythm. Based on the study of Cole et. al (2013), scapular bracing and taping are also used as another method for correcting posture. The use of elastic band for a resistance exercise program have been described to enhance the posture of every individuals. The application of resistance of the elastic band is alike from any other resistance exercise equipment such as dumbbells, kettlebell and other weighted equipment (T. W. Kim, et al, 2016). Elastic resistance bands have many advantages in the exercise and are very helpful in strength building (Pancholi, Yadav, & Kalra, 2018). Elastic band for resistance exercise program comes in different color-coded resistance and are cost-friendly, non-harmful, handy and easily accessible, and unconstraint (Wu, et al, 2018). Backpack is an ideal bag for students. The weight of the bag is symmetrically distributed on both shoulders, unlike single strap bags. For the past few years, recent studies showed that the load of backpacks used in school increases and now raises everyone’s interests, not just the child’s guardians but also among school nurses and the school administrations, since students nowadays complain of neck and back pain. Almost 12% of the world population are students wearing heavy loaded backpacks (M.J. Moore, White & D.L. Moore, 2007, as cited in Hossain & Tonima 2017) and 56.2% out of 153 students have RSP (Abkari & Gannad 2006).This study aimed to determine the effectiveness of elastic band exercises program for lengthening the pectoralis major and correcting rounded shoulder posture of teenager students of Lucena City who wear backpacks. The researcher believed that promotion of proper posture will prevent further injuries and disabilities that is associated with RSP.