This study investigated factors influencing ongoing participation in employee development activities. A multiple-indicator structural equation model building on the theory of planned behavior and prior employee development literature was tested with a survey across 4 organizations on 2 occasions. The model uses reactions to past participation and past supportiveness of the social and organizational environment as indirect antecedents of participation, filtered through their impact on attitudes and behavioral intentions toward future participation. Learning goal orientation also influenced attitudes toward participation. Whereas personal control over participation and higher levels of voluntariness were negatively related to participation, intentions to participate and availability of opportunities arose as strong predictors of higher participation rates. Many significant hypothesized paths were found, and 85% of the variance in participation was explained by the model variables. Increasing employee awareness of opportunities and managing positive attitudes toward those opportunities are recommended as key factors for increasing participation rates.