This article explores the effects of continuing professional development (CPD) on teachers' and pupils' experiences of learning and teaching science in primary classrooms. During 2006-2007, quantitative and qualitative data were elicited from two primary teachers in Scotland using questionnaires, semi-structured interviews and video-stimulated reflective dialogues (VSRD) associated with specific learning experiences. During the same period, quantitative data were elicited from 40 pupils using questionnaires and qualitative data obtained from dialogues with eight pupils in two focus groups. Two teacher interviews, four teacher-researcher dialogues and two pupil focus group interviews were audio-recorded, transcribed and coded inductively. Cultural historical activity theory (CHAT) was used as a framework for analysis of the coded data. The data indicated differences in participating teachers' views of the purposes of CPD which were reflected in their ideal and real views of effective science teaching. The combination of VSRD and CHAT made explicit the links between, and compensatory use of, formal and informal CPD and subject and pedagogical knowledge in relation to science. This enabled exploration of the influences of these factors on teachers' negotiation of barriers and constraints to teaching science through investigation and the effects on pupils' learning. As a result, reconciliation of ideal and real views of effective science teaching, identification of potential constraints and development of strategies for overcoming constraints in context are suggested as useful starting points for CPD which, it is argued, should be regarded as a career-long continuum. (Contains 9 tables and 3 notes.)