This study investigates the determinants of successful product and process innovation comparing between local firms and foreign joint ventures (FJV). Testing on the sample of 310 firms in Thai manufacturing sectors, the study found that contextual variables, business environment condition, firminternal competencies, strategic variables, and external communication are the determinants of success in innovation activities. The study discovers the different determinants between product-and processinnovative firms. Product-innovative firms maintain a broader range of innovation objectives compared to process-innovative firms. Therefore, product-innovative firms have higher degree of determinants than process-innovative firms. The study finds that FJV have better external communication enjoying the advantage of accessing technology from their parent, associated companies, and suppliers, especially in improving their production process.