Therapeutic adherence is an essential element to guarantee the best benefit/risk ratio of a drug for the patient. It refers to the degree to which the patient correctly follows the recommendations on the use of the drug at the due dosage, time, and regimen, throughout the prescribed duration. A low adherence can therefore be the consequence of an incorrect, incomplete, or irregular intake of the medicine. A high adherence, on the other hand, reduces the patient’s health risks, increases the likelihood of treatment effectiveness and safety, and contributes to controlling therapy costs. For this reason, both pharmaceutical companies and regulatory agencies have worked over the years to ensure that the patient is provided with adequate tools to minimize the likelihood and impact of low adherence to therapy. This chapter focuses on those medicines’ elements that can influence therapeutic adherence and highlights some innovations, already in place or in development, aimed to improve it. The author will privilege the example of oral drugs, which are generally self-administered by the patient at home, an environment less controlled than a clinic or hospital.