In the US, corporate lobbying as an investment with uncertainly potential payoffs has become a hot topic. There have been many academic studies about the determinants and effects of corporate lobbying. In this study, using lobbying database available from the Center for Responsive Politics and financial data from COMPUSTAT, I try to explore the determinants of lobbying activities of listed companies in the US. The results reveal that corporate lobbying spending is influenced by net income, cash flows, R&D investment, financial leverage, investment opportunity and the number of lobbying firms, but their effects vary across firm size. In addition, I find that firms are cooperative in lobbying activities, however, maintaining cooperation becomes difficult as the number of lobbying firms in the same industry rises. Furthermore, I document that large firms enjoy positive spillover effects from lobbying activities, although the benefits of spillover are tiny. These findings contribute to further understanding of lobbying activities in the US.