The present study explored the performance and psychosocial determinants of passive cancer detection behavior, that is, attentiveness to cancer symptoms, and medical help seeking, and investigated potential dependency between these two behaviors. A detailed telephone survey was conducted among 459 respondents, aged 55 years or older. The survey assessed passive detection behavior and appropriately timed medical help seeking, regarding 14 cancer symptoms. Knowledge of cancer symptoms and various other psychosocial determinants were also measured. Knowledge of cancer symptoms and adequate passive detection behavior was low to moderate. Timely medical help-seeking behavior was low to moderate for urgent symptoms but relatively high for prolonged symptoms. Overall, women had higher knowledge levels, paid more attention to cancer symptoms, and performed more timely help seeking than men. Passive detection behavior was positively associated with premotivational awareness factors (knowledge and awareness), female gender, and perceived advantages. Timely medical help seeking was positively related to cognitive motivational factors (perceived advantages, self-efficacy expectations, and intention) and negatively related to educational level and perceived susceptibility to cancer. Furthermore, a strong positive association was found between the performance of passive detection behavior and timely medical help seeking. The suboptimal levels of knowledge and performance of early cancer detection behaviors found in this study emphasize a need for educational efforts in the area of early cancer detection. The effectiveness of these efforts may benefit from considering the distinct sets of determinants of passive detection behavior and medical help seeking.