This study compared science instruction between selected science teachers from 20 junior high schools (JHS) in Ghana and the five developed countries namely: Australia, Czech Republic, Japan, Netherlands, and USA, that took part in the Third International Mathematics and Science Study (TIMSS) 1999 video study. A survey was carried out using slightly modified TIMSS 1999 video study questionnaire to compare the factors that influence science teachers' actions in Ghana with those from the five developed countries. It was revealed that science teachers from the developed countries possessed higher degrees than those from Ghana. Professional development activities of the science teachers in Ghana basically focused on science instructional techniques but are more diversed in the developed countries. Furthermore, curriculum guidelines and mandated textbooks significantly influenced decisions to teach lesson content in Ghana and Czech Republic; teachers' assessment of students' interest greatly influenced lesson content in USA; and external examination and standardized tests shaped lesson content a great deal in Ghana only.