Optimism is a crucial feature in Positive Psychology. Optimistic individuals expect good things to happen. In contrast, pessimistic individuals expect bad things to happen. Optimists and pessimists differ in many ways that have varying degrees of impact on their mental adjustment. In the past studies,  ptimistic and pessimism were regarded as the two extremes of continuous dimension. Researchers critiqued Scheier and Carver's (1985) theory of optimistic orientations overemphasized individuals' positive expectancy, neglected adaptive behaviors or damaging behaviors that extend beyond the expected beliefs (Norem & Chang, 2002). In other words, Scheier and Carver (1985) ignored mutual influences between beliefs and behaviors, as well as underestimated the possibility of various outcome behaviors. Accordingly, researchers used a variety of statistical methods to prove that optimism and pessimism should be regarded as two dimensions (Kubzansky, Kubzansky, & Maselko, 2004; Mehrabian & Ljunggren, 1997). Furthermore, Chou and Chen (2017) addressed that different combinations of expectations and coping would demonstrate different functions in mental adjustment. They adopted "positive/negative expectations" as well as "engagement/disengagement" as two dimensions based on the variable-centered approach to distinguish optimism/pessimism to "functional optimism", "dysfunctional optimism", "functional pessimism" and "dysfunctional pessimism" Furthermore, Chou and Chen (2017) found that each type of optimism/pessimism played different roles in metal adjustment. For examples, functional optimism and dysfunctional optimism positively predicted to satisfaction of life, functional pessimism negatively predicted to satisfaction of life. Functional pessimism was the best predictor to depressed and anxious symptoms. Dysfunctional optimism was the best predictor to procrastination. However, Asendorpf (2014) critiqued the paradigms of optimism studies that have generally adopted the variable-centered approach (Asendorpf, 2014); for example, Asendorpf (2014) addressed that the variable-centered approach might easily neglect the uniqueness of each individual, whereas the person-centered approach could produce trait clusters that meet ecological validity and demonstrate the behavioral characteristics related to an individual's psychological features. Thus, the study proposed while understanding the characteristics of optimistic and pessimistic traits, researchers should involve expectancy beliefs and behavioral coping as well as adopt the person-centered approach. Accordingly, the study established a scale that reflects positive and negative value of expectancy beliefs and behavioral coping, as well as further explores the differences in their mental adjustment. Study 1 sampled a total of 169 college students (female = 40.8=%, male = 59.2%) and conducted item analysis, exploratory factor analysis, internal consistency, criterion-related validity to examine the reliability and validity of "Dual-Axis Model of Optimism/Pessimism Scale-I, DAMOPS-I." The results showed that four subscales of DAMOPS-I have good reliability and validity. Study 2 enlarged the sample variability, the sample size and rewriting some contents of items, which involving a total of 639 college students (female = 54.9%, male = 44.8%). As Study 1, Study 2 conducted item analysis, exploratory factor analysis, internal consistency, criterion-related validity to examine the reliability and validity of "Dual-Axis Model of Optimism/Pessimism Scale-II, DAMOPS-II." The result indicated that the four subscales of DAMOPS-II have good reliability and validity. Furthermore, Study 2 adopted cluster analysis based on two dimensions (i.e., positive/negative expectancy and positive/negative coping behaviors) to distinguish five clusters, namely Functional Optimism, Medium Optimism, Medium Pessimism, Dysfunctional Pessimism, and Self-Handicapping. The results of Study 2 showed five types of optimism/pessimism have different levels of mental adjustment. Both of "Functional Optimism" and "Medium Optimism" had a great mental adjustment outcome. "Medium Pessimism" showed the greatest outcome within three pessimistic clusters. "Dysfunctional Pessimism" showed heightened vulnerability to mental adjustment (e.g., higher levels of depressed and anxious symptoms, lower level of life satisfaction). "Self-Handicapping" demonstrated a highest tendency to procrastinate in five clusters.