Placebos have been shown to generate beneficial effects on mental health and well-being even when they are administered openly, without deception. However, research on open-label placebos (OLPs) is limited and there is still some uncertainty regarding how OLP effects can be created consistently. A potential strategy to enhance OLP effects may be the addition of rituals, defined as a structured sequence of actions presenting goal demoted elements and symbolic meaning. Important ritualistic features (e.g., taking a pill at the same time each day with the same sequence of actions) are present across traditional, alternative, or evidence-based treatments and may enhance the placebo effect associated with these treatments. The current thesis explores OLP effects in well-being in a non-clinical population and assesses whether the addition of rituals can enhance these effects. Moreover, this research investigates the role of expectations and other factors that might be involved in OLP effects. This thesis presents four experimental studies and two survey studies. Study 1 found no OLP effects on four well-being outcomes; however, adding a ritual to OLPs had a positive effect on sleep quality. Studies 2 and 3 obtained OLP effects on all well-being outcomes: taking OLP reduced emotional distress and increased mental well-being, vigour-fatigue, and sleep quality compared to no treatment control. In Study 3, adding a ritual enhanced OLP effects on sleep quality. The two subsequent survey studies indicated that many of the rituals used in everyday life (in Study 4) and associated with taking psychotropic medications (in Study 5) were personalised by the people performing them. This finding informed Study 6, which tested the effects of personalised rituals added to OLPs on well-being. Taking OLPs generated benefits in all four well-being outcomes. Moreover, the personalised rituals enhanced OLP effects on sleep quality and emotional distress. Another important finding of this thesis is that, in Studies 3 and 6, the remote administration of OLPs without interaction between participants and the experimenter generated OLP effects comparable to those observed in Study 2, when OLPs were administered in person. Taken together, this work indicates that OLP effects can lead to benefits in well-being and adding a personalised ritual to OLPs can enhance OLP effects on sleep quality and emotional distress. The evidence presented in this thesis has relevant implications for future research in the use of OLPs and their potential applications in clinical settings.