This paper addresses the question of how alignment dynamics between niche and regime actors shape niche acceleration. We develop a conceptual framework that focuses on the role of expectations as a necessary precondition and even as a key proxy for strategic collaboration between niche and regime actors. Based on actors’ expectations, we conceptualise three alignment patterns of strong, medium-strong and weak alignment. We propose a 16 % threshold of niche technology adoption for substantial niche acceleration. We explore our conceptual framework in two contrasting case studies of wind and solar power development in China between 2000 and 2017. Both cases experienced niche acceleration but followed different paths. Our research findings indicate that the three proposed alignment patterns between niche and regime actors’ expectations can be seen as a good proxy for explaining these different paths. Strong alignment between niche and regime actors’ expectations does go hand in hand with niche acceleration.