Psychological attitudes reflecting expectations about the future (optimism, pessimism) and people (cynical hostility) independently predict incident cardiovascular disease and possibly diabetes, but underlying biologic pathways are incompletely understood. Herein we examined the cross-sectional relationship between optimism, pessimism, and cynicism and biomarkers of metabolic function in the Women’s Health Initiative. Among 3443 postmenopausal women, biomarkers of metabolic function (fasting insulin [FINS] and glucose) were measured at baseline and used to calculate insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR]) and pancreatic β-cell activity (homeostasis model assessment of β-cell function [HOMA-B]). Psychological attitudes were assessed by the Life Orientation Test, Revised (full scale, and optimism and pessimism subscales) and the Cook-Medley cynicism subscale. Multivariable linear regression modeled the association of psychological attitudes with biomarker levels, adjusting for sociodemographics, health conditions, and health behaviors. Because obesity promotes insulin resistance and obese individuals tend to report higher levels of pessimism and cynical hostility, an interaction with body mass index (BMI) was explored. In fully adjusted models, only pessimism remained independently associated with higher FINS and insulin resistance (HOMA-IR). Scoring 1 point higher on the pessimism subscale was associated with a 1.2% higher FINS, whereas scoring 1 SD higher was associated with a 2.7% higher FINS (P = 0.03); results were similar for HOMA-IR. An interaction term with BMI was not significant. In multivariable models, higher dispositional pessimism was associated with worse metabolic function; these findings were not modified by obesity status. Results extend prior work by linking pessimism to an objective biomarker of insulin resistance in elderly women.